Charged particle extraction apparatus and method of use thereof

ABSTRACT

The invention comprises a charged particle beam extraction method and apparatus optionally used in conjunction with charged particle beam radiation therapy of cancerous tumors. The system uses a radio-frequency (RF) cavity system to induce oscillation of a charged particle stream. Sufficient amplitude modulation of the charged particle stream causes the charged particle stream to hit a material, such as a foil element of a set of foils. The foil decreases the energy of the charged particle stream, which decreases a radius of curvature of the charged particle stream in the synchrotron sufficiently to allow a physical separation of the reduced energy charged particle stream from the original charged particle stream where thickness of a selected foil is a function of energy of circulating charged particles. The physically separated charged particle stream is then removed from the system by use of an applied field and deflector.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application:

-   -   is a continuation-in-part of U.S. patent application Ser. No.        12/425,683 filed Apr. 17, 2009, now U.S. Pat. No. 7,939,809,        which claims the benefit of:        -   U.S. provisional patent application No. 61/055,395 filed May            22, 2008, now U.S. Pat. No. 7,939,809 B2;        -   U.S. provisional patent application No. 61/137,574 filed            Aug. 1, 2008;        -   U.S. provisional patent application No. 61/192,245 filed            Sep. 17, 2008;        -   U.S. provisional patent application No. 61/055,409 filed May            22, 2008;        -   U.S. provisional patent application No. 61/203,308 filed            Dec. 22, 2008;        -   U.S. provisional patent application No. 61/188,407 filed            Aug. 11, 2008;        -   U.S. provisional patent application No. 61/188,406 filed            Aug. 11, 2008;        -   U.S. provisional patent application No. 61/189,815 filed            Aug. 25, 2008;        -   U.S. provisional patent application No. 61/201,731 filed            Dec. 15, 2008;        -   U.S. provisional patent application No. 61/205,362 filed            Jan. 12, 2009;        -   U.S. provisional patent application No. 61/134,717 filed            Jul. 14, 2008;        -   U.S. provisional patent application No. 61/134,707 filed            Jul. 14, 2008, now U.S. Pat. No. 7,940,894 B2;        -   U.S. provisional patent application No. 61/201,732 filed            Dec. 15, 2008, now U.S. Pat. No. 7,953,205 B2;        -   U.S. provisional patent application No. 61/198,509 filed            Nov. 7, 2008;        -   U.S. provisional patent application No. 61/134,718 filed            Jul. 14, 2008;        -   U.S. provisional patent application No. 61/190,613 filed            Sep. 2, 2008;        -   U.S. provisional patent application No. 61/191,043 filed            Sep. 8, 2008;        -   U.S. provisional patent application No. 61/192,237 filed            Sep. 17, 2008;        -   U.S. provisional patent application No. 61/201,728 filed            Dec. 15, 2008;        -   U.S. provisional patent application No. 61/190,546 filed            Sep. 2, 2008;        -   U.S. provisional patent application No. 61/189,017 filed            Aug. 15, 2008;        -   U.S. provisional patent application No. 61/198,248 filed            Nov. 5, 2008, now U.S. Pat. No. 7,943,913 B2;        -   U.S. provisional patent application No. 61/198,508 filed            Nov. 7, 2008;        -   U.S. provisional patent application No. 61/197,971 filed            Nov. 3, 2008;        -   U.S. provisional patent application No. 61/199,405 filed            Nov. 17, 2008;        -   U.S. provisional patent application No. 61/199,403 filed            Nov. 17, 2008; and        -   U.S. provisional patent application No. 61/199,404 filed            Nov. 17, 2008;    -   is a continuation-in-part of U.S. patent application Ser. No.        12/687,387 filed Jan. 14, 2010, which        -   is a continuation-in-part of U.S. patent application Ser.            No. 12/425,683 filed Apr. 17, 2009, now U.S. Pat. No.            7,939,809;        -   claims the benefit of U.S. provisional patent application            No. 61/209,529 filed Mar. 9, 2009;        -   claims the benefit of U.S. provisional patent application            No. 61/208,182 filed Feb. 23, 2009;        -   claims the benefit of U.S. provisional patent application            No. 61/208,971 filed Mar. 3, 2009; and        -   claims the benefit of U.S. provisional patent application            No. 61/270,298, filed Jul. 7, 2009;    -   is a continuation-in-part of U.S. patent application Ser. No.        12/985,039 filed Jan. 5, 2011, which        -   claims the benefit of U.S. provisional patent application            No. 61/308,621, filed Feb. 26, 2010;        -   claims the benefit of U.S. provisional patent application            No. 61/309,651, filed Mar. 2, 2010; and        -   claims the benefit of U.S. provisional patent application            No. 61/324,776, filed Apr. 16, 2010,    -   all of which are incorporated herein in their entirety by this        reference thereto.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to treatment of solid cancers. Moreparticularly, the invention relates to a multi-axis and/or multi-fieldcharged particle cancer therapy method and apparatus.

2. Discussion of the Prior Art

Cancer Treatment

Proton therapy works by aiming energetic ionizing particles, such asprotons accelerated with a particle accelerator, onto a target tumor.These particles damage the DNA of cells, ultimately causing their death.Cancerous cells, because of their high rate of division and theirreduced ability to repair damaged DNA, are particularly vulnerable toattack on their DNA.

Synchrotron

Patents related to the current invention are summarized here.

Proton Beam Therapy System

F. Cole, et. al. of Loma Linda University Medical Center “Multi-StationProton Beam Therapy System”, U.S. Pat. No. 4,870,287 (Sep. 26, 1989)describe a proton beam therapy system for selectively generating andtransporting proton beams from a single proton source and accelerator toa selected treatment room of a plurality of patient treatment rooms.

Imaging

P. Adamee, et. al. “Charged Particle Beam Apparatus and Method forOperating the Same”, U.S. Pat. No. 7,274,018 (Sep. 25, 2007) and P.Adamee, et. al. “Charged Particle Beam Apparatus and Method forOperating the Same”, U.S. Pat. No. 7,045,781 (May 16, 2006) describe acharged particle beam apparatus configured for serial and/or parallelimaging of an object.

K. Hiramoto, et. al. “Ion Beam Therapy System and its Couch PositioningSystem”, U.S. Pat. No. 7,193,227 (Mar. 20, 2007) describe an ion beamtherapy system having an X-ray imaging system moving in conjunction witha rotating gantry.

C. Maurer, et. al. “Apparatus and Method for Registration of Images toPhysical Space Using a Weighted Combination of Points and Surfaces”,U.S. Pat. No. 6,560,354 (May 6, 2003) described a process of X-raycomputed tomography registered to physical measurements taken on thepatient's body, where different body parts are given different weights.Weights are used in an iterative registration process to determine arigid body transformation process, where the transformation function isused to assist surgical or stereotactic procedures.

M. Blair, et. al. “Proton Beam Digital Imaging System”, U.S. Pat. No.5,825,845 (Oct. 20, 1998) describe a proton beam digital imaging systemhaving an X-ray source that is movable into a treatment beam line thatcan produce an X-ray beam through a region of the body. By comparison ofthe relative positions of the center of the beam in the patientorientation image and the isocentre in the master prescription imagewith respect to selected monuments, the amount and direction of movementof the patient to make the best beam center correspond to the targetisocentre is determined.

S. Nishihara, et. al. “Therapeutic Apparatus”, U.S. Pat. No. 5,039,867(Aug. 13, 1991) describe a method and apparatus for positioning atherapeutic beam in which a first distance is determined on the basis ofa first image, a second distance is determined on the basis of a secondimage, and the patient is moved to a therapy beam irradiation positionon the basis of the first and second distances.

Problem

There exists in the art of charged particle irradiation therapy a needto accurately and precisely deliver an effective and uniform radiationdose to all positions of a tumor. There further exists a need foraccurately, precisely, and timely locating and targeting a tumor in apatient. There still further exists a need in the art to control thecharged particle cancer therapy system in terms of patient translationposition, patient rotation position, specified energy, specifiedintensity, timing of charged particle delivery, and/or distribution ofradiation striking healthy tissue. Preferably, the system would operatein conjunction with a negative ion beam source, synchrotron, patientpositioning, imaging, and/or targeting method and apparatus.

SUMMARY OF THE INVENTION

The invention comprises a method and apparatus for the extraction ofcharged particles from a synchrotron.

DESCRIPTION OF THE FIGURES

A more complete understanding of the present invention is derived byreferring to the detailed description and claims when considered inconnection with the Figures, wherein like reference numbers refer tosimilar items throughout the Figures.

FIG. 1 illustrates component connections of a charged particle beamtherapy system;

FIG. 2 illustrates a charged particle therapy system;

FIG. 3 illustrates an ion beam generation system;

FIG. 4 illustrates a negative ion beam source;

FIG. 5 illustrates an ion beam focusing system;

FIGS. 6 A-D illustrate focusing electrodes about a negative ion beampath;

FIG. 7A illustrates a negative ion beam path vacuum system; FIG. 7Billustrates a support structure and foil;

FIG. 8 is a particle beam therapy control flowchart;

FIG. 9 illustrates straight and turning sections of a synchrotron

FIG. 10 illustrates bending magnets of a synchrotron;

FIG. 11 provides a perspective view of a bending magnet;

FIG. 12 illustrates a cross-sectional view of a bending magnet;

FIG. 13 illustrates a cross-sectional view of a bending magnet;

FIG. 14 illustrates magnetic field concentration in a bending magnet;

FIG. 15 illustrates correction coils in a bending magnet;

FIG. 16 illustrates a magnetic turning section of a synchrotron;

FIGS. 17A and B illustrate an RF accelerator and an RF acceleratorsubsystem, respectively;

FIG. 18A illustrates a charged particle extraction system and FIGS. 18Band 18C illustrate charged particles with different energy levelspenetrating different distances into a body;

FIG. 19 illustrates a charged particle extraction and intensity controlsystem;

FIGS. 20 A and B illustrate proton beam position verification systems;

FIG. 21 illustrates a patient positioning system from: (A) a front viewand (B) a top view;

FIG. 22 provides X-ray and proton beam dose distributions;

FIGS. 23 A-E illustrate controlled scanning and depth of focusirradiation;

FIGS. 24 A-E illustrate multi-field irradiation;

FIG. 25 illustrates dose efficiency enhancement via use of multi-fieldirradiation;

FIGS. 26 A-C and E illustrate distal irradiation of a tumor from varyingrotational directions and FIG. 26 D illustrates integrated radiationresulting from distal radiation;

FIG. 27 illustrates multi-dimensional scanning of a charged particlebeam spot scanning system operating on: (A) a 2-D slice or (B) a 3-Dvolume of a tumor;

FIG. 28 illustrates (A) irradiating varying depths within a tumor and(B) changes in irradiation intensity correlating with the varying depthsin the tumor;

FIG. 29 illustrates an electron gun source used in generating X-rayscoupled with a particle beam therapy system;

FIG. 30 illustrates an X-ray source proximate a particle beam path;

FIG. 31 illustrates an expanded X-ray beam path;

FIG. 32 provides an X-ray tomography system;

FIG. 33 illustrates a semi-vertical patient positioning system;

FIG. 34 provides an example of a sitting patient positioning system;

FIG. 35 illustrates a laying patient positioning system;

FIG. 36 illustrates a head restraint system;

FIG. 37 illustrates hand and head supports;

FIG. 38 provides a method of positioning, imaging, and irradiating atumor;

FIG. 39 provides a method of imaging a tumor with rotation of thepatient;

FIG. 40 provides a method of coordinating X-ray collection with patientrespiration;

FIG. 41 provides a method of charged particle beam control;

FIG. 42 provides a method of multi-axis charged particle beamirradiation control;

FIG. 43 illustrates a patient positioning, immobilization, andrepositioning system;

FIG. 44 shows particle field acceleration timed to a patient'srespiration cycle;

FIG. 45 illustrates adjustable particle field acceleration timing;

FIG. 46 illustrates charged particle cancer therapy controllers; and

FIG. 47 illustrates a charged particle tomography system.

Elements and steps in the figures are illustrated for simplicity andclarity and have not necessarily been rendered according to anyparticular sequence. For example, steps that are performed concurrentlyor in different order are illustrated in the figures to help improveunderstanding of embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention comprises a charged particle beam extraction method andapparatus used in conjunction with charged particle beam radiationtherapy of cancerous tumors.

The invention comprises a charged particle beam extraction method andapparatus used in conjunction with charged particle beam radiationtherapy of cancerous tumors. The system uses a radio-frequency (RF)cavity system to induce betatron oscillation of a charged particlestream. Sufficient amplitude modulation of the charged particle streamcauses the charged particle stream to hit a material, such as a foilelement of a set of foils. The foil decreases the energy of the chargedparticle stream, which decreases a radius of curvature of the chargedparticle stream in the synchrotron sufficiently to allow a physicalseparation of the reduced energy charged particle stream from theoriginal charged particle stream. Thickness of a selected foil is afunction of energy of circulating charged particles. The physicallyseparated charged particle stream is then removed from the system by useof an applied field and deflector.

Used in combination with the invention, novel design features of acharged particle beam cancer therapy system are described. Particularly,a negative ion beam source with novel features in the negative ionsource, ion source vacuum system, ion beam focusing lens, and tandemaccelerator is described. Additionally, the synchrotron includes:turning magnets, edge focusing magnets, magnetic field concentrationmagnets, winding and correction coils, flat magnetic field incidentsurfaces, and extraction elements, which minimize the overall size ofthe synchrotron, provide a tightly controlled proton beam, directlyreduce the size of required magnetic fields, directly reduce requiredoperating power, and allow continual acceleration of protons in asynchrotron even during a process of extracting protons from thesynchrotron. The ion beam source system and synchrotron are preferablycomputer integrated with a patient imaging system and a patientinterface including respiration monitoring sensors and patientpositioning elements. Further, the system is integrated with intensitycontrol of a charged particle beam, acceleration, extraction, and/ortargeting method and apparatus. More particularly, intensity, energy,and timing control of a charged particle stream of a synchrotron iscoordinated with patient positioning and tumor treatment. Thesynchrotron control elements allow tight control of the charged particlebeam, which compliments the tight control of patient positioning toyield efficient treatment of a solid tumor with reduced tissue damage tosurrounding healthy tissue. In addition, the system reduces the overallsize of the synchrotron, provides a tightly controlled proton beam,directly reduces the size of required magnetic fields, directly reducesrequired operating power, and allows continual acceleration of protonsin a synchrotron even during a process of extracting protons from thesynchrotron. All of these systems are preferably used in conjunctionwith an X-ray system capable of collecting X-rays of a patient: (1) in apositioning, immobilization, and automated repositioning system forproton treatment; (2) at a specified moment of the patient's respirationcycle; and (3) using coordinated translation and rotation of thepatient. Combined, the systems provide for efficient, accurate, andprecise noninvasive tumor treatment with minimal damage to surroundinghealthy tissue.

In various embodiments, the charged particle cancer therapy systemincorporates any of:

-   -   an injection system having a central magnetic member and a        magnetic field separating high and low temperature plasma        regions;    -   a dual vacuum system creating a first partial pressure region on        a plasma generation system side of a foil in a tandem        accelerator and a second lower partial pressure region on the        synchrotron side of the foil;    -   a negative ion beam focusing system having a conductive mesh        axially crossing the negative ion beam;    -   a synchrotron having four straight sections and four turning        sections;    -   a synchrotron having no hexapole magnets;    -   four bending magnets in each turning section of the synchrotron;    -   a winding coil wrapping multiple bending magnets;    -   a plurality of bending magnets that are beveled and charged        particle focusing in each turning section;    -   a magnetic field concentrating geometry approaching the gap        through which the charged particles travel;    -   correction coils for rapid magnetic field changes;    -   magnetic field feedback sensors providing signal to the        correction coils;    -   integrated RF-amplifier microcircuits providing currents through        loops about accelerating coils;    -   a low density foil for charged particle extraction;    -   a feedback sensor for measuring particle extraction allowing        intensity control;    -   a synchrotron independently controlling charged particle energy        and intensity;    -   a layer, after synchrotron extraction and before the tumor, for        imaging the particle beam x-, y-axis position;    -   a rotatable platform for turning the subject allowing        multi-field imaging and/or multi-field proton therapy;    -   a radiation plan dispersing ingress Bragg profile energy 360        degrees about the tumor;    -   a long lifetime X-ray source;    -   an X-ray source proximate the charged particle beam path;    -   a multi-field X-ray system;    -   positioning, immobilizing, and repositioning systems;    -   respiratory sensors;    -   simultaneous and independent control of:        -   x-axis beam control;        -   y-axis beam control;        -   irradiation beam energy;        -   irradiation beam intensity;        -   patient translation; and/or        -   patient rotation; and    -   a system timing charged particle therapy to one or more of:        -   patient translation;        -   patient rotation; and        -   patient respiration.

In another embodiment, safety systems for a charged particle system areimplemented. For example, the safety system includes any of: multipleX-ray images from multiple directions, a three-dimensional X-ray image,a proton beam approximating a path of an X-ray beam, tight control of aproton beam cross-sectional area with magnets, ability to control protonbeam energy, ability to control proton beam energy, a set of patientmovement constrains, a patient controlled charged particle interruptsystem, distribution of radiation around a tumor, and timed irradiationin terms of respiration.

In yet another embodiment, the tumor is imaged from multiple directionsin phase with patient respiration. For example, a plurality oftwo-dimensional pictures are collected that are all in the about thesame phase of respiration. The two-dimensional pictures are combined toproduce a three-dimensional picture of the tumor relative to thepatient. One or more safety features are optionally used in the chargedparticle cancer therapy system independently and/or in combination withthe three-dimensional imaging system, as described infra.

In still yet another embodiment, the system independently controlspatient translation position, patient rotation position, two-dimensionalbeam trajectory, delivered radiation beam energy, delivered radiationbeam intensity, timing of charged particle delivery, beam velocity,and/or distribution of radiation striking healthy tissue. The systemoperates in conjunction with a negative ion beam source, synchrotron,patient positioning, imaging, and/or targeting method and apparatus todeliver an effective and uniform dose of radiation to a tumor whiledistributing radiation striking healthy tissue.

Charged Particle Beam Therapy

Throughout this document, a charged particle beam therapy system, suchas a proton beam, hydrogen ion beam, or carbon ion beam, is described.Herein, the charged particle beam therapy system is described using aproton beam. However, the aspects taught and described in terms of aproton beam are not intended to be limiting to that of a proton beam andare illustrative of a charged particle beam system. Any of thetechniques described herein are equally applicable to any chargedparticle beam system.

Referring now to FIG. 1, a charged particle beam system 100 isillustrated. The charged particle beam preferably comprises a number ofsubsystems including any of: a main controller 110; an injection system120; a synchrotron 130 that typically includes: (1) an acceleratorsystem 132 and (2) an extraction system 134; ascanning/targeting/delivery system 140; a patient interface module 150;a display system 160; and/or an imaging system 170.

An exemplary method of use of the charged particle beam system 100 isprovided. The main controller 110 controls one or more of the subsystemsto accurately and precisely deliver protons to a tumor of a patient. Forexample, the main controller 110 obtains an image, such as a portion ofa body and/or of a tumor, from the imaging system 170. The maincontroller 110 also obtains position and/or timing information from thepatient interface module 150. The main controller 110 then optionallycontrols the injection system 120 to inject a proton into a synchrotron130. The synchrotron typically contains at least an accelerator system132 and an extraction system 134. The main controller 110 preferablycontrols the proton beam within the accelerator system, such as bycontrolling speed, trajectory, and timing of the proton beam. The maincontroller then controls extraction of a proton beam from theaccelerator through the extraction system 134. For example, thecontroller controls timing, energy, and/or intensity of the extractedbeam. The controller 110 also preferably controls targeting of theproton beam through the scanning/targeting/delivery system 140 to thepatient interface module 150. One or more components of the patientinterface module 150, such as translational and rotational position ofthe patient, are preferably controlled by the main controller 110.Further, display elements of the display system 160 are preferablycontrolled via the main controller 110. Displays, such as displayscreens, are typically provided to one or more operators and/or to oneor more patients. In one embodiment, the main controller 110 times thedelivery of the proton beam from all systems, such that protons aredelivered in an optimal therapeutic manner to the tumor of the patient.

Herein, the main controller 110 refers to a single system controllingthe charged particle beam system 100, to a single controller controllinga plurality of subsystems controlling the charged particle beam system100, or to a plurality of individual controllers controlling one or moresub-systems of the charged particle beam system 100.

Referring now to FIG. 2, an illustrative exemplary embodiment of oneversion of the charged particle beam system 100 is provided. The number,position, and described type of components is illustrative andnon-limiting in nature. In the illustrated embodiment, the injectionsystem 120 or ion source or charged particle beam source generatesprotons. The protons are delivered into a vacuum tube that runs into,through, and out of the synchrotron. The generated protons are deliveredalong an initial path 262. Focusing magnets 230, such as quadrupolemagnets or injection quadrupole magnets, are used to focus the protonbeam path. A quadrupole magnet is a focusing magnet. An injector bendingmagnet 232 bends the proton beam toward the plane of the synchrotron130. The focused protons having an initial energy are introduced into aninjector magnet 240, which is preferably an injection Lamberson magnet.Typically, the initial beam path 262 is along an axis off of, such asabove, a circulating plane of the synchrotron 130. The injector bendingmagnet 232 and injector magnet 240 combine to move the protons into thesynchrotron 130. Main bending magnets, dipole magnets, turning magnets,or circulating magnets 250 are used to turn the protons along acirculating beam path 264. A dipole magnet is a bending magnet. The mainbending magnets 250 bend the initial beam path 262 into a circulatingbeam path 264. In this example, the main bending magnets 250 orcirculating magnets are represented as four sets of four magnets tomaintain the circulating beam path 264 into a stable circulating beampath. However, any number of magnets or sets of magnets are optionallyused to move the protons around a single orbit in the circulationprocess. The protons pass through an accelerator 270. The acceleratoraccelerates the protons in the circulating beam path 264. As the protonsare accelerated, the fields applied by the magnets are increased.Particularly, the speed of the protons achieved by the accelerator 270are synchronized with magnetic fields of the main bending magnets 250 orcirculating magnets to maintain stable circulation of the protons abouta central point or region 280 of the synchrotron. At separate points intime the accelerator 270/main bending magnet 250 combination is used toaccelerate and/or decelerate the circulating protons while maintainingthe protons in the circulating path or orbit. An extraction element ofthe inflector/deflector system 290 is used in combination with aLamberson extraction magnet 292 to remove protons from their circulatingbeam path 264 within the synchrotron 130. One example of a deflectorcomponent is a Lamberson magnet. Typically the deflector moves theprotons from the circulating plane to an axis off of the circulatingplane, such as above the circulating plane. Extracted protons arepreferably directed and/or focused using an extraction bending magnet237 and extraction focusing magnets 235, such as quadrupole magnetsalong a transport path 268 into the scanning/targeting/delivery system140. Two components of a scanning system 140 or targeting systemtypically include a first axis control 142, such as a vertical control,and a second axis control 144, such as a horizontal control. In oneembodiment, the first axis control 142 allows for about 100 mm ofvertical or y-axis scanning of the proton beam 268 and the second axiscontrol 144 allows for about 700 mm of horizontal or x-axis scanning ofthe proton beam 268. A nozzle system 146 is used for imaging the protonbeam and/or as a vacuum barrier between the low pressure beam path ofthe synchrotron and the atmosphere. Protons are delivered with controlto the patient interface module 150 and to a tumor of a patient. All ofthe above listed elements are optional and may be used in variouspermutations and combinations. Each of the above listed elements arefurther described, infra.

Ion Beam Generation System

An ion beam generation system generates a negative ion beam, such as ahydrogen anion or H⁻ beam; preferably focuses the negative ion beam;converts the negative ion beam to a positive ion beam, such as a protonor H⁺ beam; and injects the positive ion beam 262 into the synchrotron130. Portions of the ion beam path are preferably under partial vacuum.Each of these systems are further described, infra.

Referring now to FIG. 3, an exemplary ion beam generation system 300 isillustrated. As illustrated, the ion beam generation system 300 has fourmajor subsections: a negative ion source 310, a first partial vacuumsystem 330, an optional ion beam focusing system 350, and a tandemaccelerator 390.

Still referring to FIG. 3, the negative ion source 310 preferablyincludes an inlet port 312 for injection of hydrogen gas into a hightemperature plasma chamber 314. In one embodiment, the plasma chamberincludes a magnetic material 316, which provides a magnetic field 317between the high temperature plasma chamber 314 and a low temperatureplasma region on the opposite side of the magnetic field barrier. Anextraction pulse is applied to a negative ion extraction electrode 318to pull the negative ion beam into a negative ion beam path 319, whichproceeds through the first partial vacuum system 330, through the ionbeam focusing system 350, and into the tandem accelerator 390.

Still referring to FIG. 3, the first partial vacuum system 330 is anenclosed system running from the hydrogen gas inlet port 312 to a foil395 in the tandem accelerator 390. The foil 395 is preferably sealeddirectly or indirectly to the edges of the vacuum tube 320 providing fora higher pressure, such as about 10⁻⁵ torr, to be maintained on thefirst partial vacuum system side of the foil 395 and a lower pressure,such as about 10⁻⁷ torr, to be maintained on the synchrotron side of thefoil. By only pumping first partial vacuum system 330 and by onlysemi-continuously operating the ion beam source vacuum based on sensorreadings, the lifetime of the semi-continuously operating pump isextended. The sensor readings are further described, infra.

Still referring to FIG. 3, the first partial vacuum system 330preferably includes: a first pump 332, such as a continuously operatingpump and/or a turbo molecular pump; a large holding volume 334; and asemi-continuously operating pump 336. Preferably, a pump controller 340receives a signal from a pressure sensor 342 monitoring pressure in thelarge holding volume 334. Upon a signal representative of a sufficientpressure in the large holding volume 334, the pump controller 340instructs an actuator 345 to open a valve 346 between the large holdingvolume and the semi-continuously operating pump 336 and instructs thesemi-continuously operating pump to turn on and pump to atmosphereresidual gases out of the vacuum line 320 about the charged particlestream. In this fashion, the lifetime of the semi-continuously operatingpump is extended by only operating semi-continuously and as needed. Inone example, the semi-continuously operating pump 336 operates for a fewminutes every few hours, such as 5 minutes every 4 hours, therebyextending a pump with a lifetime of about 2,000 hours to about 96,000hours.

Further, by isolating the inlet gas from the synchrotron vacuum system,the synchrotron vacuum pumps, such as turbo molecular pumps can operateover a longer lifetime as the synchrotron vacuum pumps have fewer gasmolecules to deal with. For example, the inlet gas is primarily hydrogengas but may contain impurities, such as nitrogen and carbon dioxide. Byisolating the inlet gases in the negative ion source system 310, firstpartial vacuum system 330, ion beam focusing system 350, and negativeion beam side of the tandem accelerator 390, the synchrotron vacuumpumps can operate at lower pressures with longer lifetimes, whichincreases operating efficiency of the synchrotron 130.

Still referring to FIG. 3, the optimal ion beam focusing system 350preferably includes two or more electrodes where one electrode of eachelectrode pair partially obstructs the ion beam path with conductivepaths 372, such as a conductive mesh. In the illustrated example, twoion beam focusing system sections are illustrated, a two electrode ionbeam focusing section 360 and a three electrode ion beam focusingsection 370. For a given electrode pair, electric field lines, runningbetween the conductive mesh of a first electrode and a second electrode,provide inward forces focusing the negative ion beam. Multiple suchelectrode pairs provide multiple negative ion beam focusing regions.Preferably the two electrode ion focusing section 360 and the threeelectrode ion focusing section 370 are placed after the negative ionsource and before the tandem accelerator and/or cover a space of about0.5, 1, or 2 meters along the ion beam path 319. Ion beam focusingsystems are further described, infra.

Still referring to FIG. 3, the tandem accelerator 390 preferablyincludes a foil 395, such as a carbon foil. The negative ions in thenegative ion beam path 319 are converted to positive ions, such asprotons, and the initial ion beam path 262 results. The foil 395 ispreferably sealed directly or indirectly to the edges of the vacuum tube320 providing for a higher pressure, such as about 10⁻⁵ torr, to bemaintained on the side of the foil 395 having the negative ion beam path319 and a lower pressure, such as about 10⁻⁷ torr, to be maintained onthe side of the foil 390 having the proton ion beam path 262. Having thefoil 395 physically separating the vacuum chamber 320 into two pressureregions allows for a system having fewer and/or smaller pumps tomaintain the lower pressure system in the synchrotron 130 as the inlethydrogen and its residuals are extracted in a separate contained andisolated space by the first partial vacuum system 330.

Negative Ion Source

An example of the negative ion source 310 is further described herein.Referring now to FIG. 4, a cross-section of an exemplary negative ionsource system 400 is provided. The negative ion beam 319 is created inmultiple stages. During a first stage, hydrogen gas is injected into achamber. During a second stage, a negative ion is created by applicationof a first high voltage pulse, which creates a plasma about the hydrogengas to create negative ions. During a third stage, a magnetic fieldfilter is applied to components of the plasma. During a fourth stage,the negative ions are extracted from a low temperature plasma region, onthe opposite side of the magnetic field barrier, by application of asecond high voltage pulse. Each of the four stages are furtherdescribed, infra. While the chamber is illustrated as a cross-section ofa cylinder, the cylinder is exemplary only and any geometry applies tothe magnetic loop containment walls, described infra.

In the first stage, hydrogen gas 440 is injected through the inlet port312 into a high temperature plasma region 490. The injection port 312 isopen for a short period of time, such as less than about 1, 5, or 10microseconds to minimize vacuum pump requirements to maintain vacuumchamber 320 requirements. The high temperature plasma region ismaintained at reduced pressure by the partial vacuum system 330. Theinjection of the hydrogen gas is optionally controlled by the maincontroller 110, which is responsive to imaging system 170 informationand patient interface module 150 information, such as patientpositioning and period in a respiration cycle.

In the second stage, a high temperature plasma region is created byapplying a first high voltage pulse across a first electrode 422 and asecond electrode 424. For example a 5 kV pulse is applied for about 20microseconds with 5 kV at the second electrode 424 and about 0 kVapplied at the first electrode 422. Hydrogen in the chamber is broken,in the high temperature plasma region 490, into component parts, such asany of: atomic hydrogen, H⁰, a proton, H⁺, an electron, e⁻, and ahydrogen anion, H⁻.

In the third stage, the high temperature plasma region 490 is at leastpartially separated from a low temperature plasma region 492 by themagnetic field 317 or in this specific example a magnetic field barrier430. High energy electrons are restricted from passing through themagnetic field barrier 430. In this manner, the magnetic field barrier430 acts as a filter between, zone A and zone B, in the negative ionsource. Preferably, a central magnetic material 410, which is an exampleof the magnetic material 316, is placed within the high temperatureplasma region 490, such as along a central axis of the high temperatureplasma region 490. Preferably, the first electrode 422 and secondelectrode 424 are composed of magnetic materials, such as iron.Preferably, the outer walls 450 of the high temperature plasma region,such as cylinder walls, are composed of a magnetic material, such as apermanent magnet, ferric or iron based material, or a ferrite dielectricring magnet. In this manner a magnetic field loop is created by: thecentral magnetic material 410, first electrode 422, the outer walls 450,the second electrode 424, and the magnetic field barrier 430. Again, themagnetic field barrier 430 restricts high energy electrons from passingthrough the magnetic field barrier 430. Low energy electrons interactwith atomic hydrogen, H⁰, to create a hydrogen anion, H⁻, in the lowtemperature plasma region 492.

In the fourth stage, a second high voltage pulse or extraction pulse isapplied at a third electrode 426. The second high voltage pulse ispreferentially applied during the later period of application of thefirst high voltage pulse. For example, an extraction pulse of about 25kV is applied for about the last 5 microseconds of the first creationpulse of about 20 microseconds. The potential difference, of about 20kV, between the third electrode 426 and second electrode 424 extractsthe negative ion, H⁻, from the low temperature plasma region 492 andinitiates the negative ion beam 319, from zone B to zone C.

The magnetic field barrier 430 is optionally created in number of ways.An example of creation of the magnetic field barrier 430 using coils isprovided. In this example, the elements described, supra, in relation toFIG. 4 are maintained with several differences. First, the magneticfield is created using coils. An isolating material is preferablyprovided between the first electrode 422 and the cylinder walls 450 aswell as between the second electrode 424 and the cylinder walls 450. Thecentral material 410 and/or cylinder walls 450 are optionally metallic.In this manner, the coils create a magnetic field loop through the firstelectrode 422, isolating material, outer walls 450, second electrode424, magnetic field barrier 430, and the central material 410.Essentially, the coils generate a magnetic field in place of productionof the magnetic field by the magnetic material 410. The magnetic fieldbarrier 430 operates as described, supra. Generally, any manner thatcreates the magnetic field barrier 430 between the high temperatureplasma region 490 and low temperature plasma region 492 is functionallyapplicable to the ion beam extraction system 400, described herein.

Ion Beam Focusing System

Referring now to FIG. 5, the ion beam focusing system 350 is furtherdescribed. In this example, three electrodes are used. In this example,a first electrode 510 and third electrode 530 are both negativelycharged and each is a ring electrode circumferentially enclosing or atleast partially enclosing the negative ion beam path 319. A secondelectrode 520 is positively charged and is also a ring electrode atleast partially and preferably substantially circumferentially enclosingthe negative ion beam path. In addition, the second electrode includesone or more conducting paths 372 running through the negative ion beampath 319. For example, the conducting paths are a wire mesh, aconducting grid, or a series of substantially parallel conducting linesrunning across the second electrode. In use, electric field lines runfrom the conducting paths of the positively charged electrode to thenegatively charged electrodes. For example, in use the electric fieldlines 540 run from the conducting paths 372 in the negative ion beampath 319 to the negatively charged electrodes 510, 530. Two ray tracelines 550, 560 of the negative ion beam path are used to illustratefocusing forces. In the first ray trace line 550, the negative ion beamencounters a first electric field line at point M. Negatively chargedions in the negative ion beam 550 encounter forces running up theelectric field line 572, illustrated with an x-axis component vector571. The x-axis component force vectors 571 alters the trajectory of thefirst ray trace line to a inward focused vector 552, which encounters asecond electric field line at point N. Again, the negative ion beam 552encounters forces running up the electric field line 574, illustrated ashaving an inward force vector with an x-axis component 573, which altersthe inward focused vector 552 to a more inward focused vector 554.Similarly, in the second ray trace line 560, the negative ion beamencounters a first electric field line at point O. Negatively chargedions in the negative ion beam encounter forces running up the electricfield line 576, illustrated as having a force vector with an x-axisforce 575. The inward force vector 575 alters the trajectory of thesecond ray trace line 560 to an inward focused vector 562, whichencounters a second electric field line at point P. Again, the negativeion beam encounters forces running up the electric field line 578,illustrated as having force vector with an x-axis component 577, whichalters the inward focused vector 562 to a more inward focused vector564. The net result is a focusing effect on the negative ion beam. Eachof the force vectors 572, 574, 576, 578 optionally has x and/or y forcevector components resulting in a 3-dimensional focusing of the negativeion beam path. Naturally, the force vectors are illustrative in nature,many electric field lines are encountered, and the focusing effect isobserved at each encounter resulting in integral focusing. The exampleis used to illustrate the focusing effect.

Still referring to FIG. 5, optionally any number of electrodes are used,such as 2, 3, 4, 5, 6, 7, 8, or 9 electrodes, to focus the negative ionbeam path where every other electrode, in a given focusing section, iseither positively or negatively charged. For example, three focusingsections are optionally used. In the first ion focusing section 360, apair of electrodes is used where the first electrode encountered alongthe negative ion beam path is negatively charged and the secondelectrode is positively charged, resulting in focusing of the negativeion beam path. In the second ion focusing section 370, two pairs ofelectrodes are used, where a common positively charged electrode with aconductive mesh running through the negatively ion beam path 319 isused. Thus, in the second ion focusing section 370, the first electrodeencountered along the negative ion beam path is negatively charged andthe second electrode is positively charged, resulting in focusing of thenegative ion beam path. Further, in the second ion focusing section,moving along the negative ion beam path, a second focusing effect isobserved between the second positively charged electrode and a thirdnegatively charged electrode. In this example, a third ion focusingsection is used that again has three electrodes, which acts in thefashion of the second ion focusing section, described supra.

Referring now to FIG. 6, the central region of the electrodes in the ionbeam focusing system 350 is further described. Referring now to FIG. 6A,the central region of the negatively charged ring electrode 510 ispreferably void of conductive material. Referring now to FIGS. 6B-D, thecentral region of positively charged electrode ring 520 preferablycontains conductive paths 372. Preferably, the conductive paths 372 orconductive material within the positively charged electrode ring 520blocks about 1, 2, 5, or 10 percent of the area and more preferablyblocks about five percent of the cross-sectional area of the negativeion beam path 319. Referring now to FIG. 6B, one option is a conductivemesh 610. Referring now to FIG. 6C, a second option is a series ofconductive lines 620 running substantially in parallel across thepositively charged electrode ring 520 that surrounds a portion of thenegative ion beam path 319. Referring now to FIG. 6D, a third option isto have a foil 630 or metallic layer cover all of the cross-sectionalarea of the negative ion beam path with holes punched through thematerial, where the holes take up about 90-99 percent and morepreferably about 95 percent of the area of the foil. More generally, thepair of electrodes 510, 520 are configured to provide electric fieldlines that provide focusing force vectors to the negative ion beam 319when the ions in the negative ion beam 319 translate through theelectric field lines, as described supra.

In an example of a two electrode negative beam ion focusing systemhaving a first cross-sectional diameter, d₁, the negative ions arefocused to a second cross-sectional diameter, d₂, where d₁>d₂.Similarly, in an example of a three electrode negative beam ion focusingsystem having a first ion beam cross-sectional diameter, d₁, thenegative ions are focused using the three electrode system to a thirdnegative ion beam cross-sectional diameter, d₃, where d₁>d₃. For likepotentials on the electrodes, the three electrode system providestighter or stronger focusing compared to the two-electrode system,d₃<d₂.

In the examples provided, supra, of a multi-electrode ion beam focusingsystem, the electrodes are rings. More generally, the electrodes are ofany geometry sufficient to provide electric field lines that providefocusing force vectors to the negative ion beam when the ions in thenegative ion beam 319 translate through the electric field lines, asdescribed supra. For example, one negative ring electrode is optionallyreplaced by a number of negatively charged electrodes, such as about 2,3, 4, 6, 8, 10, or more electrodes placed about the outer region of across-sectional area of the negative ion beam probe. Generally, moreelectrodes are required to converge or diverge a faster or higher energybeam.

In another embodiment, by reversing the polarity of electrodes in theabove example, the negative ion beam is made to diverge. Thus, thenegative ion beam path 319 is optionally focused and/or expanded usingcombinations of electrode pairs. For example, if the electrode havingthe mesh across the negative ion beam path is made negative, then thenegative ion beam path is made to defocus. Hence, combinations ofelectrode pairs are used for focusing and defocusing a negative ion beampath, such as where a first pair includes a positively charged mesh forfocusing and a where a second pair includes a negatively charged meshfor defocusing.

Tandem Accelerator

Referring now to FIG. 7A, the tandem accelerator 390 is furtherdescribed. The tandem accelerator accelerates ions using a series ofelectrodes 710, 711, 712, 713, 714, 715. For example, negative ions,such as H⁻, in the negative ion beam path are accelerated using a seriesof electrodes having progressively higher voltages relative to thevoltage of the extraction electrode 426, or third electrode 426, of thenegative ion beam source 310. For instance, the tandem accelerator 390optionally has electrodes ranging from the 25 kV of the extractionelectrode 426 to about 525 kV near the foil 395 in the tandemaccelerator 390. Upon passing through the foil 395, the negative ion,H⁻, loses two electrons to yield a proton, H⁺, according to equation 1.H⁻→H⁺+2e ⁻  (eq. 1)

The proton is further accelerated in the tandem accelerator usingappropriate voltages at a multitude of further electrodes 713, 714, 715.The protons are then injected into the synchrotron 130 as described,supra.

Still referring to FIG. 7, the foil 395 in the tandem accelerator 390 isfurther described. The foil 395 is preferably a very thin carbon film ofabout thirty to two hundred angstroms in thickness. The foil thicknessis designed to both: (1) not block the ion beam and (2) allow thetransfer of electrons yielding protons to form the proton beam path 262.The foil 395 is preferably substantially in contact with a support layer720, such as a support grid. The support layer 720 provides mechanicalstrength to the foil 395 to combine to form a vacuum blocking element725. The foil 395 blocks nitrogen, carbon dioxide, hydrogen, and othergases from passing and thus acts as a vacuum barrier. In one embodiment,the foil 395 is preferably sealed directly or indirectly to the edges ofthe vacuum tube 320 providing for a higher pressure, such as about 10⁻⁵torr, to be maintained on the side of the foil 395 having the negativeion beam path 319 and a lower pressure, such as about 10⁻⁷ torr, to bemaintained on the side of the foil 395 having the proton ion beam path262. Having the foil 395 physically separating the vacuum chamber 320into two pressure regions allows for a vacuum system having fewer and/orsmaller pumps to maintain the lower pressure system in the synchrotron130 as the inlet hydrogen and its residuals are extracted in a separatecontained and isolated space by the first partial vacuum system 330. Thefoil 395 and support layer 720 are preferably attached to the structure750 of the tandem accelerator 390 or vacuum tube 320 to form a pressurebarrier using any mechanical means, such as a metal, plastic, or ceramicring 730 compressed to the walls with an attachment screw 740. Anymechanical means for separating and sealing the two vacuum chamber sideswith the foil 395 are equally applicable to this system. Referring nowto FIG. 7B, the support structure 720 and foil 395 are individuallyviewed in the x-, y-plane.

Referring now to FIG. 8, another exemplary method of use of the chargedparticle beam system 100 is provided. The main controller 110, or one ormore sub-controllers, controls one or more of the subsystems toaccurately and precisely deliver protons to a tumor of a patient. Forexample, the main controller sends a message to the patient indicatingwhen or how to breathe. The main controller 110 obtains a sensor readingfrom the patient interface module, such as a temperature breath sensoror a force reading indicative of where in a respiration cycle thesubject is. Coordinated at a specific and reproducible point in therespiration cycle, the main controller collects an image, such as aportion of a body and/or of a tumor, from the imaging system 170. Themain controller 110 also obtains position and/or timing information fromthe patient interface module 150. The main controller 110 thenoptionally controls the injection system 120 to inject hydrogen gas intoa negative ion beam source 310 and controls timing of extraction of thenegative ion from the negative ion beam source 310. Optionally, the maincontroller controls ion beam focusing the ion beam focusing lens system350; acceleration of the proton beam with the tandem accelerator 390;and/or injection of the proton into the synchrotron 130. The synchrotrontypically contains at least an accelerator system 132 and an extractionsystem 134. The synchrotron preferably contains one or more of: turningmagnets, edge focusing magnets, magnetic field concentration magnets,winding and correction coils, and flat magnetic field incident surfaces,some of which contain elements under control by the main controller 110.The main controller preferably controls the proton beam within theaccelerator system, such as by controlling speed, trajectory, and/ortiming of the proton beam. The main controller then controls extractionof a proton beam from the accelerator through the extraction system 134.For example, the controller controls timing, energy, and/or intensity ofthe extracted beam. The main controller 110 also preferably controlstargeting of the proton beam through the targeting/delivery system 140to the patient interface module 150. One or more components of thepatient interface module 150 are preferably controlled by the maincontroller 110, such as vertical position of the patient, rotationalposition of the patient, and patient chairpositioning/stabilization/immobilization/control elements. Further,display elements of the display system 160 are preferably controlled viathe main controller 110. Displays, such as display screens, aretypically provided to one or more operators and/or to one or morepatients. In one embodiment, the main controller 110 times the deliveryof the proton beam from all systems, such that protons are delivered inan optimal therapeutic manner to the tumor of the patient.

Synchrotron

Herein, the term synchrotron is used to refer to a system maintainingthe charged particle beam in a circulating path. Further, the chargedparticle beam is referred to herein as circulating along a circulatingpath about a central point of the synchrotron. The circulating path isalternatively referred to as an orbiting path; however, the orbitingpath does not refer to a perfect circle or ellipse, rather it refers tocycling of the protons around a central point or region 280.

Circulating System

Referring now to FIG. 9, the synchrotron 130 preferably comprises acombination of straight sections 910 and ion beam turning sections 920.Hence, the circulating path of the protons is not circular in asynchrotron, but is rather a polygon with rounded corners.

In one illustrative embodiment, the synchrotron 130, which is alsoreferred to as an accelerator system, has four straight sections orelements and four turning sections. Examples of straight sections 910include the: inflector 240, accelerator 270, extraction system 290, anddeflector 292. Along with the four straight sections are four ion beamturning sections 920, which are also referred to as magnet sections orturning sections. Turning sections are further described, infra.

Referring still to FIG. 9, an exemplary synchrotron is illustrated. Inthis example, protons delivered along the initial proton beam path 262are inflected into the circulating beam path with the inflector 240 andafter acceleration are extracted via a deflector 292 to the beamtransport path 268. In this example, the synchrotron 130 comprises fourstraight sections 910 and four bending or turning sections 920 whereeach of the four turning sections use one or more magnets to turn theproton beam about ninety degrees. As is further described, infra, theability to closely space the turning sections and efficiently turn theproton beam results in shorter straight sections. Shorter straightsections allow for a synchrotron design without the use of focusingquadrupoles in the circulating beam path of the synchrotron. The removalof the focusing quadrupoles from the circulating proton beam pathresults in a more compact design. In this example, the illustratedsynchrotron has about a five meter diameter versus eight meter andlarger cross-sectional diameters for systems using a quadrupole focusingmagnet in the circulating proton beam path.

Referring now to FIG. 10, additional description of the first bending orturning section 920 is provided. Each of the turning sections preferablycomprise multiple magnets, such as about 2, 4, 6, 8, 10, or 12 magnets.In this example, four turning magnets 1010, 1020, 1030, 1040 in thefirst turning section 920 are used to illustrate key principles, whichare the same regardless of the number of magnets in a turning section920. The turning magnets 1010, 1020, 1030, 1040 are particular types ofmain bending or circulating magnets 250.

In physics, the Lorentz force is the force on a point charge due toelectromagnetic fields. The Lorentz force is given by equation 2 interms of magnetic fields with the electron field terms not included.F=q(v×B)  (eq. 2)

In equation 2, F is the force in Newtons; q is the electric charge incoulombs; B is the magnetic field in Teslas; and v is the instantaneousvelocity of the particles in meters per second.

Referring now to FIG. 11, an example of a single magnet bending orturning section 1010 is expanded. The turning section includes a gap1110 through which protons circulate. The gap 1110 is preferably a flatgap, allowing for a magnetic field across the gap 1110 that is moreuniform, even, and intense. A magnetic field enters the gap 1110 througha magnetic field incident surface and exits the gap 1110 through amagnetic field exiting surface. The gap 1110 runs in a vacuum tubebetween two magnet halves. The gap 1110 is controlled by at least twoparameters: (1) the gap 1110 is kept as large as possible to minimizeloss of protons and (2) the gap 1110 is kept as small as possible tominimize magnet sizes and the associated size and power requirements ofthe magnet power supplies. The flat nature of the gap 1110 allows for acompressed and more uniform magnetic field across the gap 1110. Oneexample of a gap dimension is to accommodate a vertical proton beam sizeof about two centimeters with a horizontal beam size of about five tosix centimeters.

As described, supra, a larger gap size requires a larger power supply.For instance, if the gap 1110 size doubles in vertical size, then thepower supply requirements increase by about a factor of four. Theflatness of the gap 1110 is also important. For example, the flat natureof the gap 1110 allows for an increase in energy of the extractedprotons from about 250 to about 330 MeV. More particularly, if the gap1110 has an extremely flat surface, then the limits of a magnetic fieldof an iron magnet are reachable. An exemplary precision of the flatsurface of the gap 1110 is a polish of less than about five microns andpreferably with a polish of about one to three microns. Unevenness inthe surface results in imperfections in the applied magnetic field. Thepolished flat surface spreads unevenness of the applied magnetic field.

Still referring to FIG. 11, the charged particle beam moves through thegap 1110 with an instantaneous velocity, v. A first magnetic coil 1120and a second magnetic coil 1130 run above and below the gap 1110,respectively. Current running through the coils 1120, 1130 results in amagnetic field, B, running through the single magnet turning section1010. In this example, the magnetic field, B, runs upward, which resultsin a force, F, pushing the charged particle beam inward toward a centralpoint of the synchrotron, which turns the charged particle beam in anarc.

Still referring to FIG. 11, a portion of an optional second magnetbending or turning section 1020 is illustrated. The coils 1120, 1130typically have return elements 1140, 1150 or turns at the end of onemagnet, such as at the end of the first magnet turning section 1010. Theturns 1140, 1150 take space. The space reduces the percentage of thepath about one orbit of the synchrotron that is covered by the turningmagnets. This leads to portions of the circulating path where theprotons are not turned and/or focused and allows for portions of thecirculating path where the proton path defocuses. Thus, the spaceresults in a larger synchrotron. Therefore, the space between magnetturning sections 1160 is preferably minimized. The second turning magnetis used to illustrate that the coils 1120, 1130 optionally run along aplurality of magnets, such as 2, 3, 4, 5, 6, or more magnets. Coils1120, 1130 running across multiple turning section magnets allows fortwo turning section magnets to be spatially positioned closer to eachother due to the removal of the steric constraint of the turns, whichreduces and/or minimizes the space 1160 between two turning sectionmagnets.

Referring now to FIGS. 12 and 13, two illustrative 90 degree rotatedcross-sections of single magnet bending or turning sections 1010 arepresented. The magnet assembly has a first magnet 1210 and a secondmagnet 1220. A magnetic field induced by coils, described infra, runsbetween the first magnet 1210 to the second magnet 1220 across the gap1110. Return magnetic fields run through a first yoke 1212 and secondyoke 1222. The combined cross-section area of the return yokes roughlyapproximates the cross-sectional area of the first magnet 1210 or secondmagnet 1220. The charged particles run through the vacuum tube in thegap 1110. As illustrated, protons run into FIG. 12 through the gap 1110and the magnetic field, illustrated as vector B, applies a force F tothe protons pushing the protons towards the center of the synchrotron,which is off page to the right in FIG. 12. The magnetic field is createdusing windings. A first coil is used to form a first winding coil 1250and a second coil of wire is used to form a second winding coil 1260.Isolating or concentrating gaps 1230, 1240, such as air gaps, isolatethe iron based yokes from the gap 1110. The gap 1110 is approximatelyflat to yield a uniform magnetic field across the gap 1110, as describedsupra.

Still referring to FIG. 13, the ends of a single bending or turningmagnet are preferably beveled. Nearly perpendicular or right angle edgesof a turning magnet 1010 are represented by dashed lines 1374, 1384. Thedashed lines 1374, 1384 intersect at a point 1390 beyond the center ofthe synchrotron 280. Preferably, the edge of the turning magnet isbeveled at angles alpha, α, and beta, β, which are angles formed by afirst line 1372, 1382 going from an edge of the turning magnet 1010 andthe center 280 and a second line 1374, 1384 going from the same edge ofthe turning magnet and the intersecting point 1390. The angle alpha isused to describe the effect and the description of angle alpha appliesto angle beta, but angle alpha is optionally different from angle beta.The angle alpha provides an edge focusing effect. Beveling the edge ofthe turning magnet 1010 at angle alpha focuses the proton beam.

Multiple turning magnets provide multiple magnet edges that each haveedge focusing effects in the synchrotron 130. If only one turning magnetis used, then the beam is only focused once for angle alpha or twice forangle alpha and angle beta. However, by using smaller turning magnets,more turning magnets fit into the turning sections 920 of thesynchrotron 130. For example, if four magnets are used in a turningsection 920 of the synchrotron, then for a single turning section thereare eight possible edge focusing effect surfaces, two edges per magnet.The eight focusing surfaces yield a smaller cross-sectional beam size,which allows the use of a smaller gap.

The use of multiple edge focusing effects in the turning magnets resultsin not only a smaller gap 1110, but also the use of smaller magnets andsmaller power supplies. For a synchrotron 130 having four turningsections 920 where each turning sections has four turning magnets andeach turning magnet has two focusing edges, a total of thirty-twofocusing edges exist for each orbit of the protons in the circulatingpath of the synchrotron 130. Similarly, if 2, 6, or 8 magnets are usedin a given turning section, or if 2, 3, 5, or 6 turning sections areused, then the number of edge focusing surfaces expands or contractsaccording to equation 3.

$\begin{matrix}{{TFE} = {{NTS}*\frac{M}{NTS}*\frac{FE}{M}}} & \left( {{eq}.\mspace{14mu} 3} \right)\end{matrix}$where TFE is the number of total focusing edges, NTS is the number ofturning sections, M is the number of magnets, and FE is the number offocusing edges. Naturally, not all magnets are necessarily beveled andsome magnets are optionally beveled on only one edge.

The inventors have determined that multiple smaller magnets havebenefits over fewer larger magnets. For example, the use of 16 smallmagnets yields 32 focusing edges whereas the use of 4 larger magnetsyields only 8 focusing edges. The use of a synchrotron having morefocusing edges results in a circulating path of the synchrotron builtwithout the use of focusing quadrupole magnets. All prior artsynchrotrons use quadrupoles in the circulating path of the synchrotron.Further, the use of quadrupoles in the circulating path necessitatesadditional straight sections in the circulating path of the synchrotron.Thus, the use of quadrupoles in the circulating path of a synchrotronresults in synchrotrons having larger diameters, larger circulating beampathlengths, and/or larger circumferences.

In various embodiments of the system described herein, the synchrotronhas any combination of:

-   -   at least four and preferably six, eight, ten, or more edge        focusing edges per 90 degrees of turn of the charged particle        beam in a synchrotron having four turning sections;    -   at least about sixteen and preferably about twenty-four,        thirty-two, or more edge focusing edges per orbit of the charged        particle beam in the synchrotron;    -   only four turning sections where each of the turning sections        includes at least four and preferably eight edge focusing edges;    -   an equal number of straight sections and turning sections;    -   exactly four turning sections;    -   at least four focusing edges per turning section;    -   no quadrupoles in the circulating path of the synchrotron;    -   a rounded corner rectangular polygon configuration;    -   a circumference of less than sixty meters;    -   a circumference of less than sixty meters and thirty-two edge        focusing surfaces; and/or    -   any of about eight, sixteen, twenty-four, or thirty-two        non-quadrupole magnets per circulating path of the synchrotron,        where the non-quadrupole magnets include edge focusing edges.        Flat Gap Surface

While the gap surface is described in terms of the first turning magnet1010, the discussion applies to each of the turning magnets in thesynchrotron. Similarly, while the gap 1110 surface is described in termsof the magnetic field incident surface 1270, the discussion additionallyoptionally applies to the magnetic field exiting surface 1280.

Referring again to FIG. 12, the incident magnetic field surface 1270 ofthe first magnet 1210 is further described. FIG. 12 is not to scale andis illustrative in nature. Local imperfections or unevenness in qualityof the finish of the incident surface 1270 results in inhomogeneities orimperfections in the magnetic field applied to the gap 1110. Themagnetic field incident surface 1270 and/or exiting surface 1280 of thefirst magnet 1210 is preferably about flat, such as to within about azero to three micron finish polish or less preferably to about a tenmicron finish polish. By being very flat, the polished surface spreadsthe unevenness of the applied magnetic field across the gap 1110. Thevery flat surface, such as about 0, 1, 2, 4, 6, 8, 10, 15, or 20 micronfinish, allows for a smaller gap size, a smaller applied magnetic field,smaller power supplies, and tighter control of the proton beamcross-sectional area.

Referring now to FIG. 14, additional optional magnet elements, of themagnet cross-section illustratively represented in FIG. 12, aredescribed. The first magnet 1210 preferably contains an initialcross-sectional distance 1410 of the iron based core. The contours ofthe magnetic field are shaped by the magnets 1210, 1220 and the yokes1212, 1222. The iron based core tapers to a second cross-sectionaldistance 1420. The shape of the magnetic field vector 1440 isillustrative only. The magnetic field in the magnet preferentially staysin the iron based core as opposed to the gaps 1230, 1240. As thecross-sectional distance decreases from the initial cross-sectionaldistance 1410 to the final cross-sectional distance 1420, the magneticfield concentrates. The change in shape of the magnet from the longerdistance 1410 to the smaller distance 1420 acts as an amplifier. Theconcentration of the magnetic field is illustrated by representing aninitial density of magnetic field vectors 1430 in the initialcross-section 1410 to a concentrated density of magnetic field vectors1440 in the final cross-section 1420. The concentration of the magneticfield due to the geometry of the turning magnets results in fewerwinding coils 1250, 1260 being required and also a smaller power supplyto the coils being required.

In one example, the initial cross-section distance 1410 is about fifteencentimeters and the final cross-section distance 1420 is about tencentimeters. Using the provided numbers, the concentration of themagnetic field is about 15/10 or 1.5 times at the incident surface 1270of the gap 1110, though the relationship is not linear. The taper 1460has a slope, such as about twenty, forty, or sixty degrees. Theconcentration of the magnetic field, such as by 1.5 times, leads to acorresponding decrease in power consumption requirements to the magnets.

Referring now to FIG. 15, an additional example of geometry of themagnet used to concentrate the magnetic field is illustrated. Asillustrated in FIG. 14, the first magnet 1210 preferably contains aninitial cross-sectional distance 1410 of the iron based core. Thecontours of the magnetic field are shaped by the magnets 1210, 1220 andthe yokes 1212, 1222. In this example, the core tapers to a secondcross-sectional distance 1420 with a smaller angle theta, θ. Asdescribed, supra, the magnetic field in the magnet preferentially staysin the iron based core as opposed to the gaps 1230, 1240. As thecross-sectional distance decreases from the initial cross-sectionaldistance 1410 to the final cross-sectional distance 1420, the magneticfield concentrates. The smaller angle, theta, results in a greateramplification of the magnetic field in going from the longer distance1410 to the smaller distance 1420. The concentration of the magneticfield is illustrated by representing an initial density of magneticfield vectors 1430 in the initial cross-section 1410 to a concentrateddensity of magnetic field vectors 1440 in the final cross-section 1420.The concentration of the magnetic field due to the geometry of theturning magnets results in fewer winding coils 1250, 1260 being requiredand also a smaller power supply to the winding coils 1250, 1260 beingrequired.

Still referring to FIG. 15, optional correction coils 1510, 1520 areillustrated that are used to correct the strength of one or more turningmagnets. The correction coils 1520, 1530 supplement the winding coils1250, 1260. The correction coils 1510, 1520 have correction coil powersupplies that are separate from winding coil power supplies used withthe winding coils 1250, 1260. The correction coil power suppliestypically operate at a fraction of the power required compared to thewinding coil power supplies, such as about 1, 2, 3, 5, 7, or 10 percentof the power and more preferably about 1 or 2 percent of the power usedwith the winding coils 1250, 1260. The smaller operating power appliedto the correction coils 1510, 1520 allows for more accurate and/orprecise control of the correction coils. The correction coils are usedto adjust for imperfection in the turning magnets. Optionally, separatecorrection coils are used for each turning magnet allowing individualtuning of the magnetic field for each turning magnet, which easesquality requirements in the manufacture of each turning magnet.

Referring now to FIG. 16, an example of winding coils 1630 andcorrection coils 1620 about a plurality of turning magnets 1010, 1020 inan ion beam turning section 920 is illustrated. The winding coilspreferably cover 1, 2, or 4 turning magnets. One or more high precisionmagnetic field sensors 1650 are placed into the synchrotron and are usedto measure the magnetic field at or near the proton beam path. Forexample, the magnetic sensors are optionally placed between turningmagnets and/or within a turning magnet, such as at or near the gap 1110or at or near the magnet core or yoke. The sensors are part of afeedback system to the correction coils, which is optionally run by themain controller. Thus, the system preferably stabilizes the magneticfield in the synchrotron rather than stabilizing the current applied tothe magnets. Stabilization of the magnetic field allows the synchrotronto come to a new energy level quickly. This allows the system to becontrolled to an operator or algorithm selected energy level with eachpulse of the synchrotron and/or with each breath of the patient.

The winding and/or correction coils correct one, two, three, or fourturning magnets, and preferably correct a magnetic field generated bytwo turning magnets. Optionally, a correction coil 1640 winds a singlemagnet section 1010 or a correction coil 1620 winds two or more magnetturning sections 1010, 1020. A winding or correction coil coveringmultiple magnets reduces space between magnets as fewer winding orcorrection coil ends are required, which occupy space. Reduction ofspace between turning magnets allows operation of the turning magnetswith smaller power supplies and optionally without quadrupole magnetfocusing sections.

Space 1160 at the end of a turning magnets 1010, 1040 is optionallyfurther reduced by changing the cross-sectional shape of the windingcoils. For example, when the winding coils are running longitudinallyalong the length of the circulating path or along the length of theturning magnet, the cross-sectional dimension is thick and when thewinding coils turn at the end of a turning magnet to run axially acrossthe winding coil, then the cross-sectional area of the winding coils ispreferably thin. For example, the cross-sectional area of winding coilsas measured by an m×n matrix is 3×2 running longitudinally along theturning magnet and 6×1 running axially at the end of the turning magnet,thereby reducing the width of the coils, n, while keeping the number ofcoils constant. Preferably, the turn from the longitudinal to axialdirection of the winding coil approximates ninety degrees by cuttingeach winding and welding each longitudinal section to the connectingaxial section at about a ninety degree angle. The nearly perpendicularweld further reduces space requirements of the turn in the winding coil,which reduces space in circulating orbit not experiencing focusing andturning forces, which reduces the size of the synchrotron.

Referring now to FIG. 17A and FIG. 17B, the accelerator system 270, suchas a radio-frequency (RF) accelerator system, is further described. Theaccelerator includes a series of coils 1710-1719, such as iron orferrite coils, each circumferentially enclosing the vacuum system 320through which the proton beam 264 passes in the synchrotron 130.Referring now to FIG. 17B, the first coil 1710 is further described. Aloop of standard wire 1730 completes at least one turn about the firstcoil 1710. The loop attaches to a microcircuit 1720. Referring again toFIG. 17A, an RF synthesizer 1740, which is preferably connected to themain controller 110, provides a low voltage RF signal that issynchronized to the period of circulation of protons in the proton beampath 264. The RF synthesizer 1740, microcircuit 1720, loop 1730, andcoil 1710 combine to provide an accelerating voltage to the protons inthe proton beam path 264. For example, the RF synthesizer 1740 sends asignal to the microcircuit 1720, which amplifies the low voltage RFsignal and yields an acceleration voltage, such as about 10 volts. Theactual acceleration voltage for a single microcircuit/loop/coilcombination is about five, ten, fifteen, or twenty volts, but ispreferably about ten volts. Preferably, the RF-amplifier microcircuitand accelerating coil are integrated.

Still referring to FIG. 17A, the integrated RF-amplifier microcircuitand accelerating coil presented in FIG. 17B is repeated, as illustratedas the set of coils 1711-1719 surrounding the vacuum tube 320. Forexample, the RF-synthesizer 1740, under main controller 130 direction,sends an RF-signal to the microcircuits 1720-1729 connected to coils1710-1719, respectively. Each of the microcircuit/loop/coil combinationsgenerates a proton accelerating voltage, such as about ten volts each.Hence, a set of five coil combinations generates about fifty volts forproton acceleration. Preferably about five to twentymicrocircuit/loop/coil combinations are used and more preferably aboutnine or ten microcircuit/loop/coil combinations are used in theaccelerator system 270.

As a further clarifying example, the RF synthesizer 1740 sends anRF-signal, with a period equal to a period of circulation of a protonabout the synchrotron 130, to a set of ten microcircuit/loop/coilcombinations, which results in about 100 volts for acceleration of theprotons in the proton beam path 264. The 100 volts is generated at arange of frequencies, such as at about one MHz for a low energy protonbeam to about fifteen MHz for a high energy proton beam. The RF-signalis optionally set at an integer multiple of a period of circulation ofthe proton about the synchrotron circulating path. Each of themicrocircuit/loop/coil combinations are optionally independentlycontrolled in terms of acceleration voltage and frequency.

Integration of the RF-amplifier microcircuit and accelerating coil, ineach microcircuit/loop/coil combination, results in three considerableadvantages. First, for synchrotrons, the prior art does not usemicrocircuits integrated with the accelerating coils but rather uses aset of long cables to provide power to a corresponding set of coils. Thelong cables have an impedance/resistance, which is problematic for highfrequency RF control. As a result, the prior art system is not operableat high frequencies, such as above about ten MHz. The integratedRF-amplifier microcircuit/accelerating coil system is operable at aboveabout ten MHz and even fifteen MHz where the impedance and/or resistanceof the long cables in the prior art systems results in poor control orfailure in proton acceleration. Second, the long cable system, operatingat lower frequencies, costs about $50,000 and the integratedmicrocircuit system costs about $1000, which is fifty times lessexpensive. Third, the microcircuit/loop/coil combinations in conjunctionwith the RF-amplifier system results in a compact low power consumptiondesign allowing production and use of a proton cancer therapy system ina small space, as described supra, and in a cost effective manner.

Referring again to FIG. 16, an example of a winding coil 1630 thatcovers two turning magnets 1010, 1020 is provided. Optionally, a firstwinding coil 1640 covers two magnets 1010, 1020 and a second windingcoil, not illustrated, covers another two magnets 1030, 1040. Asdescribed, supra, this system reduces space between turning sectionallowing more magnetic field to be applied per radian of turn. A firstcorrection coil 1640 is illustrated that is used to correct the magneticfield for the first turning magnet 1010. A second correction coil 1620is illustrated that is used to correct the magnetic field for a windingcoil 1630 about two turning magnets. Individual correction coils foreach turning magnet are preferred and individual correction coils yieldthe most precise and/or accurate magnetic field in each turning section.Particularly, an individual correction coil is preferably used tocompensate for imperfections in the individual magnet of a given turningsection. Hence, with a series of magnetic field sensors, correspondingmagnetic fields are individually adjustable in a series of feedbackloops, via a magnetic field monitoring system, as an independent coil isused for each turning section. Alternatively, a multiple magnetcorrection coil is used to correct the magnetic field for a plurality ofturning section magnets.

Proton Beam Extraction

Referring now to FIG. 18A, an exemplary proton beam extraction process1800 from the synchrotron 130 is illustrated. For clarity, FIG. 18removes elements represented in FIG. 2, such as the turning magnets,which allows for greater clarity of presentation of the proton beam pathas a function of time. Generally, protons are extracted from thesynchrotron 130 by slowing the protons. As described, supra, the protonswere initially accelerated in a circulating path 264, which ismaintained with a plurality of main bending magnets 250. The circulatingpath is referred to herein as an original central beamline 264. Theprotons repeatedly cycle around a central point in the synchrotron 280.The proton path traverses through a radio frequency (RF) cavity system1910. To initiate extraction, an RF field is applied across a firstblade 1912 and a second blade 1914, in the RF cavity system 1910. Thefirst blade 1912 and second blade 1914 are referred to herein as a firstpair of blades.

In the proton extraction process, an RF voltage is applied across thefirst pair of blades, where the first blade 1912 of the first pair ofblades is on one side of the circulating proton beam path 264 and thesecond blade 1914 of the first pair of blades is on an opposite side ofthe circulating proton beam path 264. The applied RF field appliesenergy to the circulating charged-particle beam. The applied RF fieldalters the orbiting or circulating beam path slightly of the protonsfrom the original central beamline 264 to an altered circulating beampath 265. Upon a second pass of the protons through the RF cavitysystem, the RF field further moves the protons off of the originalproton beamline 264. For example, if the original beamline is consideredas a circular path, then the altered beamline is slightly elliptical.The applied RF field is timed to apply outward or inward movement to agiven band of protons circulating in the synchrotron accelerator. Eachorbit of the protons is slightly more off axis compared to the originalcirculating beam path 264. Successive passes of the protons through theRF cavity system are forced further and further from the originalcentral beamline 264 by altering the direction and/or intensity of theRF field with each successive pass of the proton beam through the RFfield.

The RF voltage is frequency modulated at a frequency about equal to theperiod of one proton cycling around the synchrotron for one revolutionor at a frequency than is an integral multiplier of the period of oneproton cycling about the synchrotron. The applied RF frequency modulatedvoltage excites a betatron oscillation. For example, the oscillation isa sine wave motion of the protons. The process of timing the RF field toa given proton beam within the RF cavity system is repeated thousands oftimes with each successive pass of the protons being moved approximatelyone micrometer further off of the original central beamline 264. Forclarity, the approximately 1000 changing beam paths with each successivepath of a given band of protons through the RF field are illustrated asthe altered beam path 265.

With a sufficient sine wave betatron amplitude, the altered circulatingbeam path 265 touches and/or traverses a material 1930, such as a foilor a sheet of foil. The foil is preferably a lightweight material, suchas beryllium, a lithium hydride, a carbon sheet, or a material havinglow nuclear charge components. Herein, a material of low nuclear chargeis a material composed of atoms consisting essentially of atoms havingsix or fewer protons. The foil is preferably about 10 to 150 micronsthick, is more preferably about 30 to 100 microns thick, and is stillmore preferably about 40 to 60 microns thick. In one example, the foilis beryllium with a thickness of about 50 microns. When the protonstraverse through the foil, energy of the protons is lost and the speedof the protons is reduced. Typically, a current is also generated,described infra. Protons moving at a slower speed travel in thesynchrotron with a reduced radius of curvature 266 compared to eitherthe original central beamline 264 or the altered circulating path 265.The reduced radius of curvature 266 path is also referred to herein as apath having a smaller diameter of trajectory or a path having protonswith reduced energy. The reduced radius of curvature 266 is typicallyabout two millimeters less than a radius of curvature of the last passof the protons along the altered proton beam path 265.

The thickness of the material 1930 is optionally adjusted to created achange in the radius of curvature, such as about ½, 1, 2, 3, or 4 mmless than the last pass of the protons 265 or original radius ofcurvature 264. Protons moving with the smaller radius of curvaturetravel between a second pair of blades. In one case, the second pair ofblades is physically distinct and/or is separated from the first pair ofblades. In a second case, one of the first pair of blades is also amember of the second pair of blades. For example, the second pair ofblades is the second blade 1914 and a third blade 1916 in the RF cavitysystem 1910. A high voltage DC signal, such as about 1 to 5 kV, is thenapplied across the second pair of blades, which directs the protons outof the synchrotron through an extraction magnet 292, such as a Lambersonextraction magnet, into a transport path 268.

Still referring to FIG. 18A, in one example, the material 1930 is a setof foils with different foils having different thicknesses. For example,a first foil 1932 has a thickness less than a thickness of a second foil1934 and the second foil 1934 has a thickness less than a thickness of athird foil 1936. Each of the foils 1932, 1934, 1936 optionally has anyof the properties of the material 1930, described supra. The energy ofthe charged particles in the altered circulating beam path 265 ispreferably in the range of about 70 to 250 MeV. Optionally, a thinnerextraction foil is used in the extraction system with lower energycharged particles and a thicker foil is used in the extraction system1800 with higher energy charged particles. For example, the first foil1932 having a thickness of about 30 to 70 micrometers and preferablyabout 50 micrometers is used in the extraction of charged particleshaving energy of about 70 to 150 MeV, the second foil 1934 having athickness of about 60 to 140 micrometers and preferably about 100micrometers is used in the extraction of charged particles having energyof about 150 to 200 MeV, and the third foil having a thickness of about150 to 250 micrometers and preferably about 200 micrometers is used inthe extraction of charged particles having energy of about 70 to 150MeV. Any number of foils are optionally used. Similarly, various membersof the set of foils have varying densities. For example, a second foilhas a density about 110, 120, 130, 150, 200, or 300 percent of a densityof a first foil. For a given thickness, the denser foil is used inextraction of higher energy charged particles. Similarly, the foils varyin both density and thickness.

Still referring to FIG. 18A, each of the foils 1932, 1934, 1936 isoptionally moved toward or away from the circulating charged particlebeam path 264 prior to and/or in the process of charged particleextraction, such as with one or more actuators. Preferably, the foilactuated toward the circulating beam path 264 is selected to have alarger thickness as a function of higher energy of the charged particlesin the beam path, as described infra.

Referring now to FIG. 18B and FIG. 18C, in use a thinner foil, such asthe first foil 1932, is used for lower energy levels, such as depictedby E₁ to traverse a short distance through a patient 2130 or a shortdistance through tissue to a tumor 2120. Similarly, in use a mediumthickness foil, such as the second foil 1934, is used for medium levelsof energy of the charged particles, such as depicted by E₂ to traverse amedium distance through a patient 2130 or a medium distance throughtissue to the tumor 2120. Further, in use a thicker foil, such as thethird foil 1936, is used for higher energy levels charged particles,such as depicted by E₃ to traverse a larger distance through a patient2130 or a larger distance through tissue to the tumor 2120.

Control of acceleration of the charged particle beam path in thesynchrotron with the accelerator and/or applied fields of the turningmagnets in combination with the above described extraction system allowsfor control of the intensity of the extracted proton beam, whereintensity is a proton flux per unit time or the number of protonsextracted as a function of time. For example, when a current is measuredbeyond a threshold, the RF field modulation in the RF cavity system isterminated or reinitiated to establish a subsequent cycle of proton beamextraction. This process is repeated to yield many cycles of proton beamextraction from the synchrotron accelerator.

In another embodiment, instead of moving the charged particles to thematerial 1930, the material 1930 is mechanically moved to thecirculating charged particles. Particularly, the material 1930 ismechanically or electromechanically translated into the path of thecirculating charged particles to induce the extraction process,described supra.

In either case, because the extraction system does not depend on anychange in magnetic field properties, it allows the synchrotron tocontinue to operate in acceleration or deceleration mode during theextraction process. Stated differently, the extraction process does notinterfere with synchrotron acceleration. In stark contrast, traditionalextraction systems introduce a new magnetic field, such as via ahexapole, during the extraction process. More particularly, traditionalsynchrotrons have a magnet, such as a hexapole magnet, that is offduring an acceleration stage. During the extraction phase, the hexapolemagnetic field is introduced to the circulating path of the synchrotron.The introduction of the magnetic field necessitates two distinct modes,an acceleration mode and an extraction mode, which are mutuallyexclusive in time. The herein described system allows for accelerationand/or deceleration of the proton during the extraction step without theuse of a newly introduced magnetic field, such as by a hexapole magnet.

Charged Particle Beam Intensity Control

Control of applied field, such as a radio-frequency (RF) field,frequency and magnitude in the RF cavity system 1910 allows forintensity control of the extracted proton beam, where intensity isextracted proton flux per unit time or the number of protons extractedas a function of time.

Referring now to FIG. 19, an intensity control system 1900 isillustrated. In this example, an intensity control feedback loop isadded to the extraction system, described supra. When protons in theproton beam hit the material 1930 electrons are given off resulting in acurrent. The resulting current is converted to a voltage and is used aspart of a ion beam intensity monitoring system or as part of an ion beamfeedback loop for controlling beam intensity. The voltage is optionallymeasured and sent to the main controller 110 or to an intensitycontroller subsystem 1940, which is preferably in communication or underthe direction of the main controller 110. More particularly, whenprotons in the charged particle beam path pass through the material1930, some of the protons lose a small fraction of their energy, such asabout one-tenth of a percent, which results in a secondary electron.That is, protons in the charged particle beam push some electrons whenpassing through material 1930 giving the electrons enough energy tocause secondary emission. The resulting electron flow results in acurrent or signal that is proportional to the number of protons goingthrough the target material 1930. The resulting current is preferablyconverted to voltage and amplified. The resulting signal is referred toas a measured intensity signal.

The amplified signal or measured intensity signal resulting from theprotons passing through the material 1930 is optionally used inmonitoring the intensity of the extracted protons and is preferably usedin controlling the intensity of the extracted protons. For example, themeasured intensity signal is compared to a goal signal, which ispredetermined in an irradiation of the tumor plan. The differencebetween the measured intensity signal and the planned for goal signal iscalculated. The difference is used as a control to the RF generator.Hence, the measured flow of current resulting from the protons passingthrough the material 1930 is used as a control in the RF generator toincrease or decrease the number of protons undergoing betatronoscillation and striking the material 1930. Hence, the voltagedetermined off of the material 1930 is used as a measure of the orbitalpath and is used as a feedback control to control the RF cavity system.

In one example, the intensity controller subsystem 1940 preferablyadditionally receives input from: (1) a detector 1950, which provides areading of the actual intensity of the proton beam and (2) anirradiation plan 1960. The irradiation plan provides the desiredintensity of the proton beam for each x, y, energy, and/or rotationalposition of the patient/tumor as a function of time. Thus, the intensitycontroller 1940 receives the desired intensity from the irradiation plan1950, the actual intensity from the detector 1950 and/or a measure ofintensity from the material 1930, and adjusts the radio-frequency fieldin the RF cavity system 1910 to yield an intensity of the proton beamthat matches the desired intensity from the irradiation plan 1960.

As described, supra, the photons striking the material 1930 is a step inthe extraction of the protons from the synchrotron 130. Hence, themeasured intensity signal is used to change the number of protons perunit time being extracted, which is referred to as intensity of theproton beam. The intensity of the proton beam is thus under algorithmcontrol. Further, the intensity of the proton beam is controlledseparately from the velocity of the protons in the synchrotron 130.Hence, intensity of the protons extracted and the energy of the protonsextracted are independently variable.

For example, protons initially move at an equilibrium trajectory in thesynchrotron 130. An RF field is used to excite the protons into abetatron oscillation. In one case, the frequency of the protons orbit isabout 10 MHz. In one example, in about one millisecond or after about10,000 orbits, the first protons hit an outer edge of the targetmaterial 130. The specific frequency is dependent upon the period of theorbit. Upon hitting the material 130, the protons push electrons throughthe foil to produce a current. The current is converted to voltage andamplified to yield a measured intensity signal. The measured intensitysignal is used as a feedback input to control the applied RF magnitude,RF frequency, or RF field. Preferably, the measured intensity signal iscompared to a target signal and a measure of the difference between themeasured intensity signal and target signal is used to adjust theapplied RF field in the RF cavity system 1910 in the extraction systemto control the intensity of the protons in the extraction step. Statedagain, the signal resulting from the protons striking and/or passingthrough the material 130 is used as an input in RF field modulation. Anincrease in the magnitude of the RF modulation results in protonshitting the foil or material 130 sooner. By increasing the RF, moreprotons are pushed into the foil, which results in an increasedintensity, or more protons per unit time, of protons extracted from thesynchrotron 130.

In another example, a detector 1950 external to the synchrotron 130 isused to determine the flux of protons extracted from the synchrotron anda signal from the external detector is used to alter the RF field or RFmodulation in the RF cavity system 1910. Here the external detectorgenerates an external signal, which is used in a manner similar to themeasured intensity signal, described in the preceding paragraphs.Preferably, an algorithm or irradiation plan 1960 is used as an input tothe intensity controller 1940, which controls the RF field modulation bydirecting the RF signal in the betatron oscillation generation in the RFcavity system 1910. The irradiation plan 1960 preferably includes thedesired intensity of the charged particle beam as a function of time,energy of the charged particle beam as a function of time, for eachpatient rotation position, and/or for each x-, y-position of the chargedparticle beam.

In yet another example, when a current from material 130 resulting fromprotons passing through or hitting material is measured beyond athreshold, the RF field modulation in the RF cavity system is terminatedor reinitiated to establish a subsequent cycle of proton beamextraction. This process is repeated to yield many cycles of proton beamextraction from the synchrotron accelerator.

In still yet another embodiment, intensity modulation of the extractedproton beam is controlled by the main controller 110. The maincontroller 110 optionally and/or additionally controls timing ofextraction of the charged particle beam and energy of the extractedproton beam.

The benefits of the system include a multi-dimensional scanning system.Particularly, the system allows independence in: (1) energy of theprotons extracted and (2) intensity of the protons extracted. That is,energy of the protons extracted is controlled by an energy controlsystem and an intensity control system controls the intensity of theextracted protons. The energy control system and intensity controlsystem are optionally independently controlled. Preferably, the maincontroller 110 controls the energy control system and the maincontroller 110 simultaneously controls the intensity control system toyield an extracted proton beam with controlled energy and controlledintensity where the controlled energy and controlled intensity areindependently variable. Thus the irradiation spot hitting the tumor isunder independent control of:

-   -   time;    -   energy;    -   intensity;    -   x-axis position, where the x-axis represents horizontal movement        of the proton beam relative to the patient, and    -   y-axis position, where the y-axis represents vertical movement        of the proton beam relative to the patient.

In addition, the patient is optionally independently translated and/orrotated relative to a translational axis of the proton beam at the sametime.

Referring now to FIGS. 20 A and B, a proton beam position verificationsystem 2000 is described. A nozzle 2010 provides an outlet for thesecond reduced pressure vacuum system initiating at the foil 395 of thetandem accelerator 390 and running through the synchrotron 130 to anozzle foil 2020 covering the end of the nozzle 2010. The nozzle expandsin x-, y-cross-sectional area along the z-axis of the proton beam path268 to allow the proton beam 268 to be scanned along the x- and y-axesby the vertical control element 142 and horizontal control element 144,respectively. The nozzle foil 2020 is preferably mechanically supportedby the outer edges of an exit port of the nozzle 2010. An example of anozzle foil 2020 is a sheet of about 0.1 inch thick aluminum foil.Generally, the nozzle foil separates atmosphere pressures on the patientside of the nozzle foil 2020 from the low pressure region, such as about10⁻⁵ to 10⁻⁷ torr region, on the synchrotron 130 side of the nozzle foil2020. The low pressure region is maintained to reduce scattering of theproton beam 264, 268.

Still referring to FIG. 20, the proton beam verification system 2000 isa system that allows for monitoring of the actual proton beam position268, 269 in real-time without destruction of the proton beam. The protonbeam verification system 2000 preferably includes a proton beam positionverification layer 2030, which is also referred to herein as a coating,luminescent, fluorescent, phosphorescent, radiance, or viewing layer.The verification layer or coating layer 2030 is preferably a coating orthin layer substantially in contact with an inside surface of the nozzlefoil 2020, where the inside surface is on the synchrotron side of thenozzle foil 2020. Less preferably, the verification layer or coatinglayer 2030 is substantially in contact with an outer surface of thenozzle foil 2020, where the outer surface is on the patient treatmentside of the nozzle foil 2020. Preferably, the nozzle foil 2020 providesa substrate surface for coating by the coating layer. Optionally, abinding layer is located between the coating layer 2030 and the nozzlefoil 2020. Optionally a separate coating layer support element, on whichthe coating 2030 is mounted, is placed anywhere in the proton beam path268.

Referring now to FIG. 20B, the coating 2030 yields a measurablespectroscopic response, spatially viewable by the detector 2040, as aresult of transmission by the proton beam 268. The coating 2030 ispreferably a phosphor, but is optionally any material that is viewableor imaged by a detector where the material changes spectroscopically asa result of the proton beam path 268 hitting or transmitting through thecoating 2030. A detector or camera 2040 views the coating layer 2030 anddetermines the current position of the proton beam 269 by thespectroscopic differences resulting from protons passing through thecoating layer. For example, the camera 2040 views the coating surface2030 as the proton beam 268 is being scanned by the horizontal 144 andvertical 142 beam position control elements during treatment of thetumor 2120. The camera 2040 views the current position of the protonbeam 269 as measured by spectroscopic response. The coating layer 2030is preferably a phosphor or luminescent material that glows or emitsphotons for a short period of time, such as less than 5 seconds for a50% intensity, as a result of excitation by the proton beam 268.Optionally, a plurality of cameras or detectors 2040 are used, whereeach detector views all or a portion of the coating layer 2030. Forexample, two detectors 2040 are used where a first detector views afirst half of the coating layer and the second detector views a secondhalf of the coating layer. Preferably, at least a portion of thedetector 2040 is mounted into the nozzle 2010 to view the proton beamposition after passing through the first axis and second axiscontrollers 142, 144. Preferably, the coating layer 2030 is positionedin the proton beam path 268 in a position prior to the protons strikingthe patient 2130.

Still referring to FIG. 20, the main controller 130, connected to thecamera or detector 2040 output, compares the actual proton beam position269 with the planned proton beam position and/or a calibration referenceto determine if the actual proton beam position 269 is within tolerance.The proton beam verification system 2000 preferably is used in at leasttwo phases, a calibration phase and a proton beam treatment phase. Thecalibration phase is used to correlate, as a function of x-, y-positionof the glowing response the actual x-, y-position of the proton beam atthe patient interface. During the proton beam treatment phase, theproton beam position is monitored and compared to the calibration and/ortreatment plan to verify accurate proton delivery to the tumor 2120and/or as a proton beam shutoff safety indicator.

Patient Positioning

Referring now to FIG. 21, the patient is preferably positioned on orwithin a patient translation and rotation positioning system 2110 of thepatient interface module 150. The patient translation and rotationpositioning system 2110 is used to translate the patient and/or rotatethe patient into a zone where the proton beam can scan the tumor using ascanning system 140 or proton targeting system, described infra.Essentially, the patient positioning system 2110 performs largemovements of the patient to place the tumor near the center of a protonbeam path 268 and the proton scanning or targeting system 140 performsfine movements of the momentary beam position 269 in targeting the tumor2120. To illustrate, FIG. 21A shows the momentary proton beam position269 and a range of scannable positions 2140 using the proton scanning ortargeting system 140, where the scannable positions 2140 are about thetumor 2120 of the patient 2130. In this example, the scannable positionsare scanned along the x- and y-axes; however, scanning is optionallysimultaneously performed along the z-axis as described infra. Thisillustratively shows that the y-axis movement of the patient occurs on ascale of the body, such as adjustment of about 1, 2, 3, or 4 feet, whilethe scannable region of the proton beam 268 covers a portion of thebody, such as a region of about 1, 2, 4, 6, 8, 10, or 12 inches. Thepatient positioning system and its rotation and/or translation of thepatient combines with the proton targeting system to yield preciseand/or accurate delivery of the protons to the tumor.

Referring still to FIG. 21, the patient positioning system 2110optionally includes a bottom unit 2112 and a top unit 2114, such asdiscs or a platform. Referring now to FIG. 21A, the patient positioningunit 2110 is preferably y-axis adjustable 2116 to allow verticalshifting of the patient relative to the proton therapy beam 268.Preferably, the vertical motion of the patient positioning unit 2110 isabout 10, 20, 30, or 50 centimeters per minute. Referring now to FIG.21B, the patient positioning unit 2110 is also preferably rotatable 2117about a rotation axis, such as about the y-axis running through thecenter of the bottom unit 2112 or about a y-axis running through thetumor 2120, to allow rotational control and positioning of the patientrelative to the proton beam path 268. Preferably the rotational motionof the patient positioning unit 2110 is about 360 degrees per minute.Optionally, the patient positioning unit rotates about 45, 90, or 180degrees. Optionally, the patient positioning unit 2110 rotates at a rateof about 45, 90, 180, 360, 720, or 1080 degrees per minute. The rotationof the positioning unit 2117 is illustrated about the rotation axis attwo distinct times, t₁ and t₂. Protons are optionally delivered to thetumor 2120 at n times where each of the n times represent a differentrelative direction of the incident proton beam 269 hitting the patient2130 due to rotation of the patient 2117 about the rotation axis.

Any of the semi-vertical, sitting, or laying patient positioningembodiments described, infra, are optionally vertically translatablealong the y-axis or rotatable about the rotation or y-axis.

Preferably, the top and bottom units 2112, 2114 move together, such thatthey rotate at the same rates and translate in position at the samerates. Optionally, the top and bottom units 2112, 2114 are independentlyadjustable along the y-axis to allow a difference in distance betweenthe top and bottom units 2112, 2114. Motors, power supplies, andmechanical assemblies for moving the top and bottom units 2112, 2114 arepreferably located out of the proton beam path 269, such as below thebottom unit 2112 and/or above the top unit 2114. This is preferable asthe patient positioning unit 2110 is preferably rotatable about 360degrees and the motors, power supplies, and mechanical assembliesinterfere with the protons if positioned in the proton beam path 269

Proton Delivery Efficiency

Referring now to FIG. 22, a common distribution of relative doses forboth X-rays and proton irradiation is presented. As shown, X-raysdeposit their highest dose near the surface of the targeted tissue andthen deposited doses exponentially decrease as a function of tissuedepth. The deposition of X-ray energy near the surface is non-ideal fortumors located deep within the body, which is usually the case, asexcessive damage is done to the soft tissue layers surrounding the tumor2120. The advantage of protons is that they deposit most of their energynear the end of the flight trajectory as the energy loss per unit pathof the absorber transversed by a proton increases with decreasingparticle velocity, giving rise to a sharp maximum in ionization near theend of the range, referred to herein as the Bragg peak. Furthermore,since the flight trajectory of the protons is variable by increasing ordecreasing the initial kinetic energy or initial velocity of the proton,then the peak corresponding to maximum energy is movable within thetissue. Thus z-axis control of the proton depth of penetration isallowed by the acceleration/extraction process, described supra. As aresult of proton dose-distribution characteristics, using the algorithmdescribed, infra, a radiation oncologist can optimize dosage to thetumor 2120 while minimizing dosage to surrounding normal tissues.

Herein, the term ingress refers to a place charged particles enter intothe patient 2130 or a place of charged particles entering the tumor2120. The ingress region of the Bragg energy profile refers to therelatively flat dose delivery portion at shallow depths of the Braggenergy profile. Similarly, herein the terms proximal or the clauseproximal region refer to the shallow depth region of the tissue thatreceives the relatively flat radiation dose delivery portion of thedelivered Bragg profile energy. Herein, the term distal refers to theback portion of the tumor located furthest away from the point of originwhere the charged particles enter the tumor. In terms of the Braggenergy profile, the Bragg peak is at the distal point of the profile.Herein, the term ventral refers to the front of the patient and the termdorsal refers to the back of the patient. As an example of use, whendelivering protons to a tumor in the body, the protons ingress throughthe healthy tissue and if delivered to the far side of the tumor, theBragg peak occurs at the distal side of the tumor. For a case where theproton energy is not sufficient to reach the far side of the tumor, thedistal point of the Bragg energy profile is the region of furthestpenetration into the tumor.

The Bragg peak energy profile shows that protons deliver their energyacross the entire length of the body penetrated by the proton up to amaximum penetration depth. As a result, energy is being delivered, inthe proximal portion of the Bragg peak energy profile, to healthytissue, bone, and other body constituents before the proton beam hitsthe tumor. It follows that the shorter the pathlength in the body priorto the tumor, the higher the efficiency of proton delivery efficiency,where proton delivery efficiency is a measure of how much energy isdelivered to the tumor relative to healthy portions of the patient.Examples of proton delivery efficiency include: (1) a ratio of protonenergy delivered to the tumor over proton energy delivered to non-tumortissue; (2) pathlength of protons in the tumor versus pathlength in thenon-tumor tissue; and/or (3) damage to a tumor compared to damage tohealthy body parts. Any of these measures are optionally weighted bydamage to sensitive tissue, such as a nervous system element, heart,brain, or other organ. To illustrate, for a patient in a laying positionwhere the patient is rotated about the y-axis during treatment, a tumornear the heart would at times be treated with protons running throughthe head-to-heart path, leg-to-heart path, or hip-to-heart path, whichare all inefficient compared to a patient in a sitting or semi-verticalposition where the protons are all delivered through a shorterchest-to-heart; side-of-body-to-heart, or back-to-heart path.Particularly, compared to a laying position, using a sitting orsemi-vertical position of the patient, a shorter pathlength through thebody to a tumor is provided to a tumor located in the torso or head,which results in a higher or better proton delivery efficiency.

Herein proton delivery efficiency is separately described from timeefficiency or synchrotron use efficiency, which is a fraction of timethat the charged particle beam apparatus is in a tumor treatingoperation mode.

Depth Targeting

Referring now to FIGS. 23 A-E, x-axis scanning of the proton beam isillustrated while z-axis energy of the proton beam undergoes controlledvariation 2300 to allow irradiation of slices of the tumor 2120. Forclarity of presentation, the simultaneous y-axis scanning that isperformed is not illustrated. In FIG. 23A, irradiation is commencingwith the momentary proton beam position 269 at the start of a firstslice. Referring now to FIG. 23B, the momentary proton beam position isat the end of the first slice. Importantly, during a given slice ofirradiation, the proton beam energy is preferably continuouslycontrolled and changed according to the tissue mass and density in frontof the tumor 2120. The variation of the proton beam energy to accountfor tissue density thus allows the beam stopping point, or Bragg peak,to remain inside the tissue slice. The variation of the proton beamenergy during scanning or during x-, y-axes scanning is possible due tothe acceleration/extraction techniques, described supra, which allow foracceleration of the proton beam during extraction. FIGS. 23C, 23D, and23E show the momentary proton beam position in the middle of the secondslice, two-thirds of the way through a third slice, and after finalizingirradiation from a given direction, respectively. Using this approach,controlled, accurate, and precise delivery of proton irradiation energyto the tumor 2120, to a designated tumor subsection, or to a tumor layeris achieved. Efficiency of deposition of proton energy to tumor, asdefined as the ratio of the proton irradiation energy delivered to thetumor relative to the proton irradiation energy delivered to the healthytissue is further described infra.

Multi-Field Irradiation

It is desirable to maximize efficiency of deposition of protons to thetumor 2120, as defined by maximizing the ratio of the proton irradiationenergy delivered to the tumor 2120 relative to the proton irradiationenergy delivered to the healthy tissue. Irradiation from one, two, orthree directions into the body, such as by rotating the body about 90degrees between irradiation sub-sessions results in proton irradiationfrom the proximal portion of the Bragg peak concentrating into one, two,or three healthy tissue volumes, respectively. It is desirable tofurther distribute the proximal portion of the Bragg peak energy evenlythrough the healthy volume tissue surrounding the tumor 2120.

Multi-field irradiation is proton beam irradiation from a plurality ofentry points into the body. For example, the patient 2130 is rotated andthe radiation source point is held constant. For example, the patient2130 is rotated through 360 degrees and proton therapy is applied from amultitude of angles resulting in the ingress or proximal radiation beingcircumferentially spread about the tumor yielding enhanced protonirradiation efficiency. In one case, the body is rotated into greaterthan 3, 5, 10, 15, 20, 25, 30, or 35 positions and proton irradiationoccurs with each rotation position. Rotation of the patient ispreferably performed using the patient positioning system 2110 and/orthe bottom unit 2112 or disc, described supra. Rotation of the patient2130 while keeping the delivery proton beam 268 in a relatively fixedorientation allows irradiation of the tumor 2120 from multipledirections without use of a new collimator for each direction. Further,as no new setup is required for each rotation position of the patient2130, the system allows the tumor 2120 to be treated from multipledirections without reseating or positioning the patient, therebyminimizing tumor 2120 regeneration time, increasing the synchrotronsefficiency, and increasing patient throughput.

The patient is optionally centered on the bottom unit 2112 or the tumor2120 is optionally centered on the bottom unit 2112. If the patient iscentered on the bottom unit 2112, then the first axis control element142 and second axis control element 144 are programmed to compensate forthe off central axis of rotation position variation of the tumor 2120.

Referring now to FIGS. 24 A-E, an example of multi-field irradiation2400 is presented. In this example, five patient rotation positions areillustrated; however, the five rotation positions are discrete rotationpositions of about thirty-six rotation positions, where the body isrotated about ten degrees with each position. Referring now to FIG. 24A,a range of irradiation beam positions 269 is illustrated from a firstbody rotation position, illustrated as the patient 2130 facing theproton irradiation beam where the tumor receives the bulk of the Braggprofile energy while a first healthy volume 2411 is irradiated by theless intense ingress portion of the Bragg profile energy. Referring nowto FIG. 24B, the patient 2130 is rotated about forty degrees and theirradiation is repeated. In the second position, the tumor 2120 againreceives the bulk of the irradiation energy and a second healthy tissuevolume 2412 receives the smaller ingress portion of the Bragg profileenergy. Referring now to FIGS. 24 C-E, the patient 2130 is rotated atotal of about 90, 130, and 180 degrees, respectively. For each of thethird, fourth, and fifth rotation positions, the tumor 2120 receives thebulk of the irradiation energy and the third, fourth, and fifth healthytissue volumes 2413, 2414, 1415 receive the smaller ingress portion ofthe Bragg peak energy, respectively. Thus, the rotation of the patientduring proton therapy results in the proximal or ingress energy of thedelivered proton energy to be distributed about the tumor 2120, such asto regions one to five 2411-2415, while along a given axis, at leastabout 75, 80, 85, 90, or 95 percent of the energy is delivered to thetumor 2120.

For a given rotation position, all or part of the tumor is irradiated.For example, in one embodiment only a distal section or distal slice ofthe tumor 2120 is irradiated with each rotation position, where thedistal section is a section furthest from the entry point of the protonbeam into the patient 2130. For example, the distal section is thedorsal side of the tumor when the patient 2130 is facing the proton beamand the distal section is the ventral side of the tumor when the patient2130 is facing away from the proton beam.

Referring now to FIG. 25, a second example of multi-field irradiation2500 is presented where the proton source is stationary and the patient2130 is rotated. For ease of presentation, the stationary but scanningproton beam path 269 is illustrated as entering the patient 2130 fromvarying sides at times t₁, t₂, t₃, . . . , t_(n), t_(n+1) as the patientis rotated. At a first time, t₁, the ingress side or proximal region ofthe Bragg peak profile hits a first area, A₁. Again, the proximal end ofthe Bragg peak profile refers to the relatively shallow depths of tissuewhere Bragg energy profile energy delivery is relatively flat. Thepatient is rotated and the proton beam path is illustrated at a secondtime, t₂, where the ingress energy of the Bragg energy profile hits asecond area, A₂. Thus, the low radiation dosage of the ingress region ofthe Bragg profile energy is delivered to the second area. At a thirdtime, the ingress end of the Bragg energy profile hits a third area, A₃.This rotation and irradiation process is repeated n times, where n is apositive number greater than five and preferably greater than about 10,20, 30, 100, or 300. As illustrated, at an n^(th) time, t_(n), if thepatient 2130 is rotated further, the scanning proton beam 269 would hita sensitive body constituent 2150, such as the spinal cord or eyes.Irradiation is preferably suspended until the sensitive body constituentis rotated out of the scanning proton beam 269 path. Irradiation isresumed at a time, t_(n+1), after the sensitive body constituent 2150 isrotated out of the proton beam path. In this manner:

-   -   the distal Bragg peak energy is always within the tumor;    -   the radiation dose delivery of the distal region of the Bragg        energy profile is spread over the tumor;    -   the ingress or proximal region of the Bragg energy profile is        distributed in healthy tissue about the tumor 2120; and    -   sensitive body constituents 2150 receive minimal or no proton        beam irradiation.        Proton Delivery Efficiency

Herein, charged particle or proton delivery efficiency is radiation dosedelivered to the tumor compared to radiation dose delivered to thehealthy regions of the patient.

A proton delivery enhancement method is described where proton deliveryefficiency is enhanced, optimized, or maximized. In general, multi-fieldirradiation is used to deliver protons to the tumor from a multitude ofrotational directions. From each direction, the energy of the protons isadjusted to target the distal portion of the tumor, where the distalportion of the tumor is the volume of the tumor furthest from the entrypoint of the proton beam into the body.

For clarity, the process is described using an example where the outeredges of the tumor are initially irradiated using distally appliedradiation through a multitude of rotational positions, such as through360 degrees. This results in a symbolic or calculated remaining smallertumor for irradiation. The process is then repeated as many times asnecessary on the smaller tumor. However, the presentation is forclarity. In actuality, irradiation from a given rotational angle isperformed once with z-axis proton beam energy and intensity beingadjusted for the calculated smaller inner tumors during x- and y-axisscanning.

Referring now to FIG. 26, the proton delivery enhancement method isfurther described. Referring now to FIG. 26A, at a first point in timeprotons are delivered to the tumor 2120 of the patient 2130 from a firstdirection. From the first rotational direction, the proton beam isscanned 269 across the tumor. As the proton beam is scanned across thetumor the energy of the proton beam is adjusted to allow the Bragg peakenergy to target the distal portion of the tumor. Again, distal refersto the back portion of the tumor located furthest away from where thecharged particles enter the tumor. As illustrated, the proton beam isscanned along an x-axis across the patient. This process allows theBragg peak energy to fall within the tumor, for the middle area of theBragg peak profile to fall in the middle and proximal portion of thetumor, and for the small intensity ingress portion of the Bragg peak tohit healthy tissue. In this manner, the maximum radiation dose isdelivered to the tumor or the proton dose efficiency is maximized forthe first rotational direction.

After irradiation from the first rotational position, the patient isrotated to a new rotational position. Referring now to FIG. 26B, thescanning of the proton beam is repeated. Again, the distal portion ofthe tumor is targeted with adjustment of the proton beam energy totarget the Bragg peak energy to the distal portion of the tumor.Naturally, the distal portion of the tumor for the second rotationalposition is different from the distal portion of the tumor for the firstrotational position. Referring now to FIG. 26C, the process of rotatingthe patient and then irradiating the new distal portion of the tumor isfurther illustrated at an n^(th) rotational position. Preferably, theprocess of rotating the patient and scanning along the x- and y-axeswith the Z-axes energy targeting the new distal portion of the tumor isrepeated, such as with more than 5, 10, 20, or 30 rotational positionsor with about 36 rotational positions.

For clarity, FIGS. 26A-C and FIG. 26 E show the proton beam as havingmoved, but in actuality, the proton beam is stationary and the patientis rotated, such as via use of rotating the bottom unit 2112 of thepatient positioning system 2110. Also, FIGS. 26A-C and FIG. 26E show theproton beam being scanned across the tumor along the x-axis. Though notillustrated for clarity, the proton beam is additionally scanned up anddown the tumor along the y-axis of the patient. Combined, the distalportion or volume of the tumor is irradiated along the x- and y-axeswith adjustment of the z-axis energy level of the proton beam. In onecase, the tumor is scanned along the x-axis and the scanning is repeatedalong the x-axis for multiple y-axis positions. In another case, thetumor is scanned along the y-axis and the scanning is repeated along they-axis for multiple x-axis positions. In yet another case, the tumor isscanned by simultaneously adjusting the x- and y-axes so that the distalportion of the tumor is targeted. In all of these cases, the z-axis orenergy of the proton beam is adjusted along the contour of the distalportion of the tumor to target the Bragg peak energy to the distalportion of the tumor.

Referring now to FIG. 26D, after targeting the distal portion of thetumor from multiple directions, such as through 360 degrees, the outerperimeter of the tumor has been strongly irradiated with peak Braggprofile energy, the middle of the Bragg peak energy profile energy hasbeen delivered along an inner edge of the heavily irradiated tumorperimeter, and smaller dosages from the ingress portion of the Braggenergy profile are distributed throughout the tumor and into somehealthy tissue. The delivered dosages or accumulated radiation fluxlevels are illustrated in a cross-sectional area of the tumor 2120 usingan iso-line plot. After a first full rotation of the patient,symbolically, the darkest regions of the tumor are nearly fullyirradiated and the regions of the tissue having received less radiationare illustrated with a gray scale with the whitest portions having thelowest radiation dose.

Referring now to FIG. 26E, after completing the distal targetingmulti-field irradiation, a smaller inner tumor is defined, where theinner tumor is already partially irradiated. The smaller inner tumor isindicated by the dashed line 2630. The above process of irradiating thetumor is repeated for the newly defined smaller tumor. The protondosages to the outer or distal portions of the smaller tumor areadjusted to account for the dosages delivered from other rotationalpositions. After the second tumor is irradiated, a yet smaller thirdtumor is defined. The process is repeated until the entire tumor isirradiated at the prescribed or defined dosage.

As described at the onset of this example, the patient is preferablyonly rotated to each rotational position once. In the above describedexample, after irradiation of the outer perimeter of the tumor, thepatient is rotationally positioned, such as through 360 degrees, and thedistal portion of the newest smaller tumor is targeted as described,supra. However, the irradiation dosage to be delivered to the secondsmaller tumor and each subsequently smaller tumor is known a-priori.Hence, when at a given angle of rotation, the smaller tumor or multipleprogressively smaller tumors, are optionally targeted so that thepatient is only rotated to the multiple rotational irradiation positionsonce.

The goal is to deliver a treatment dosage to each position of the tumor,to preferably not exceed the treatment dosage to any position of thetumor, to minimize ingress radiation dosage to healthy tissue, tocircumferentially distribute ingress radiation hitting the healthytissue, and to further minimize ingress radiation dosage to sensitiveareas. Since the Bragg energy profile is known, it is possible tocalculated the optimal intensity and energy of the proton beam for eachrotational position and for each x- and y-axis scanning position. Thesecalculation result in slightly less than threshold radiation dosage tobe delivered to the distal portion of the tumor for each rotationalposition as the ingress dose energy from other positions bring the totaldose energy for the targeted position up to the threshold delivery dose.

Referring again to FIG. 26A and FIG. 26C, the intensity of the protonbeam is preferably adjusted to account for the cross-sectional distanceor density of the healthy tissue. An example is used for clarity.Referring now to FIG. 26A, when irradiating from the first positionwhere the healthy tissue has a small area 2610, the intensity of theproton beam is preferably increased as relatively less energy isdelivered by the ingress portion of the Bragg profile to the healthytissue. Referring now to FIG. 26C, in contrast when irradiating from then^(th) rotational position where the healthy tissue has a largecross-sectional area 2620, the intensity of the proton beam ispreferably decreased as a greater fraction the proton dose is deliveredto the healthy tissue from this orientation.

In one example, for each rotational position and/or for each z-axisdistance into the tumor, the efficiency of proton dose delivery to thetumor is calculated. The intensity of the proton beam is madeproportional to the calculated efficiency. Essentially, when thescanning direction has really good efficiency, the intensity isincreased and vise-versa. For example, if the tumor is elongated,generally the efficiency of irradiating the distal portion by goingthrough the length of the tumor is higher than irradiating a distalregion of the tumor by going across the tumor with the Bragg energydistribution. Generally, in the optimization algorithm:

-   -   distal portions of the tumor are targeted for each rotational        position;    -   the intensity of the proton beam is largest with the largest        cross-sectional area of the tumor;    -   intensity is larger when the intervening healthy tissue volume        is smallest; and    -   intensity is minimized or cut to zero when the intervening        healthy tissue volume includes sensitive tissue, such as the        spinal cord or eyes.

Using an algorithm so defined, the efficiency of radiation dose deliveryto the tumor is maximized. More particularly, the ratio of radiationdose delivered to the tumor versus the radiation dose delivered tosurrounding healthy tissue approaches a maximum. Further, integratedradiation dose delivery to each x, y, and z-axis volume of the tumor asa result of irradiation from multiple rotation directions is at or nearthe preferred dose level. Still further, ingress radiation dose deliveryto healthy tissue is circumferentially distributed about the tumor viause of multi-field irradiation where radiation is delivered from aplurality of directions into the body, such as more than 5, 10, 20, or30 directions.

Multi-Field Irradiation

In one multi-field irradiation example, the particle therapy system witha synchrotron ring diameter of less than six meters includes ability to:

-   -   rotate the patient through about 360 degrees;    -   extract radiation in about 0.1 to 10 seconds;    -   scan vertically about 100 millimeters;    -   scan horizontally about 700 millimeters;    -   vary beam energy from about 30 to 330 MeV/second during        irradiation;    -   vary the proton beam intensity independently of varying the        proton beam energy;    -   focus the proton beam with a cross-sectional distance from about        2 to 20 millimeters at the tumor; and/or    -   complete multi-field irradiation of a tumor in less than about        1, 2, 4, or 6 minutes as measured from the time of initiating        proton delivery to the patient 2130.

Two multi-field irradiation methods are described. In the first method,the main controller 110 rotationally positions the patient 2130 andsubsequently irradiates the tumor 2120. The process is repeated until amulti-field irradiation plan is complete. In the second method, the maincontroller 110 simultaneously rotates and irradiates the tumor 2120within the patient 2130 until the multi-field irradiation plan iscomplete. More particularly, the proton beam irradiation occurs whilethe patient 2130 is being rotated.

The 3-dimensional scanning system of the proton spot focal point,described herein, is preferably combined with a rotation/raster method.The method includes layer wise tumor irradiation from many directions.During a given irradiation slice, the proton beam energy is continuouslychanged according to the tissue's density in front of the tumor toresult in the beam stopping point, defined by the Bragg peak, alwaysbeing inside the tumor and inside the irradiated slice. The novel methodallows for irradiation from many directions, referred to herein asmulti-field irradiation, to achieve the maximal effective dose at thetumor level while simultaneously significantly reducing possibleside-effects on the surrounding healthy tissues in comparison toexisting methods. Essentially, the multi-field irradiation systemdistributes dose-distribution at tissue depths not yet reaching thetumor.

Proton Beam Position Control

Referring now to FIG. 27A, a beam delivery and tissue volume scanningsystem is illustrated. Presently, the worldwide radiotherapy communityuses a method of dose field forming using a pencil beam scanning system.In stark contrast, FIG. 27 illustrates a spot scanning system or tissuevolume scanning system. In the tissue volume scanning system, the protonbeam is controlled, in terms of transportation and distribution, usingan inexpensive and precise scanning system. The scanning system is anactive system, where the beam is focused into a spot focal point ofabout one-half, one, two, or three millimeters in diameter. The focalpoint is translated along two axes while simultaneously altering theapplied energy of the proton beam, which effectively changes the thirddimension of the focal point. The system is applicable in combinationwith the above described rotation of the body, which preferably occursin-between individual moments or cycles of proton delivery to the tumor.Optionally, the rotation of the body by the above described systemoccurs continuously and simultaneously with proton delivery to thetumor.

For example, in the illustrated system in FIG. 27A, the spot istranslated horizontally, is moved down a vertical y-axis, and is thenback along the horizontal axis. In this example, current is used tocontrol a vertical scanning system having at least one magnet. Theapplied current alters the magnetic field of the vertical scanningsystem to control the vertical deflection of the proton beam. Similarly,a horizontal scanning magnet system controls the horizontal deflectionof the proton beam. The degree of transport along each axes iscontrolled to conform to the tumor cross-section at the given depth. Thedepth is controlled by changing the energy of the proton beam. Forexample, the proton beam energy is decreased, so as to define a newpenetration depth, and the scanning process is repeated along thehorizontal and vertical axes covering a new cross-sectional area of thetumor. Combined, the three axes of control allow scanning or movement ofthe proton beam focal point over the entire volume of the canceroustumor. The time at each spot and the direction into the body for eachspot is controlled to yield the desired radiation does at eachsub-volume of the cancerous volume while distributing energy hittingoutside of the tumor.

The focused beam spot volume dimension is preferably tightly controlledto a diameter of about 0.5, 1, or 2 millimeters, but is alternativelyseveral centimeters in diameter. Preferred design controls allowscanning in two directions with: (1) a vertical amplitude of about 100mm amplitude and frequency up to about 200 Hz; and (2) a horizontalamplitude of about 700 mm amplitude and frequency up to about 1 Hz.

Proton Beam Energy Control

In FIG. 27A, the proton beam is illustrated along a z-axis controlled bythe beam energy, the horizontal movement is along an x-axis, and thevertical direction is along a y-axis. The distance the protons movealong the z-axis into the tissue, in this example, is controlled by thekinetic energy of the proton. This coordinate system is arbitrary andexemplary. Referring now to FIG. 27B, preferably control of the protonbeam is controlled in 3-dimensional space using two scanning magnetsystems and by simultaneously varying and controlling the kinetic energyof the proton beam. The use of the extraction system, described supra,allows for different scanning patterns. Particularly, the system allowssimultaneous adjustment of the x-, y-, and z-axes in the irradiation ofthe solid tumor. Stated again, instead of scanning along an x,y-planeand then adjusting energy of the protons, such as with a rangemodulation wheel, the system allows for moving along the z-axes whilesimultaneously adjusting the x- and or y-axes. Hence, rather thanirradiating slices of the tumor, the tumor is optionally irradiated inthree simultaneous dimensions. For example, the tumor is irradiatedaround an outer edge of the tumor in three dimensions. Then the tumor isirradiated around an outer edge of an internal section of the tumor.This process is repeated until the entire tumor is irradiated. The outeredge irradiation is preferably coupled with simultaneous rotation of thesubject, such as about a vertical y-axis. This system allows for maximumefficiency of deposition of protons to the tumor, as defined as theratio of the proton irradiation energy delivered to the tumor relativeto the proton irradiation energy delivered to the healthy tissue.

Combined, the system allows for multi-axes control of the chargedparticle beam system in a small space with a low or small power supply.For example, the system uses multiple magnets where each magnet has atleast one edge focusing effect in each turning section of thesynchrotron and/or multiple magnets having concentrating magnetic fieldgeometry, as described supra. The multiple edge focusing effects in thecirculating beam path of the synchrotron combined with the concentrationgeometry of the magnets and described extraction system yields asynchrotron having:

-   -   a small circumference system, such as less than about 50 meters;    -   a vertical proton beam size gap of about 2 cm;    -   corresponding reduced power supply requirements associated with        the reduced gap size;    -   an extraction system not requiring a newly introduced magnetic        field;    -   acceleration or deceleration of the protons during extraction;        and    -   control of z-axis energy during extraction.

The result is a 3-dimensional scanning system, x-, y-, and z-axescontrol, where the z-axes control resides in the synchrotron and wherethe z-axes energy is variably controlled during the extraction processinside the synchrotron.

Proton Beam Intensity Control

Referring now to FIG. 28, an intensity modulated 3-dimensional scanningsystem 2800 is described. Referring now to FIG. 28A, a proton beam isbeing scanned across and x- and/or y-axis as a function of time. Witheach time, the z-axis energy is optionally adjusted. In this case, fromthe first time, t₁, to the third time, t₃, the energy is increased, andfrom the third time, t₃, to the fifth time, t₅, the energy is decreased.Thus, the system is scanning in 3-dimensions along the x-, y-, and/orz-axes. Notably, the radiation energy delivery efficiency is increasingfrom t₁ to t₃ and decreasing from t₃ to t₅, where efficiency refers tothe percentage of radiation delivered to the tumor. For example, at thethird time, t₃, the Bragg peak energy is located at the distal, or back,portion of the tumor located furthest away from the point of originwhere the charged particles enter the tumor 2120. Delivered Bragg peakenergy increases exponentially up to the maximum distance of protonenergy penetration into the body. Hence, as illustrated the percentageof the delivered Bragg peak energy in the tumor is greatest at the thirdtime period t₃, which has the largest tumor cross-section pathlength,less at the second and fourth time periods, t₂ and t₄, and still less atthe first and fifth time periods, t₁ and t₅, which have the smallesttumor cross-section pathlength Referring now to FIG. 28B, the intensityof the proton beam is also changing with time in a manner correlatedwith the radiation energy delivery efficiency. In this case, theintensity of the proton beam is greatest at the third time period t₃,less at the second and fourth time periods, t₂ and t₄, and still less atthe first and fifth time periods, t₁ and t₅. The intensity of the protonbeam is adjusted to be more intense when radiation delivery efficiencyincreases using the proton beam extraction process 1800 and intensitycontrol system 1900, described supra. Intensity is generally positivelycorrelated with tumor cross-sectional pathlength, proton beam energy,and/or radiation delivery efficiency. Preferably, the distal portion ofthe tumor is targeted with each rotational position of the patient 2130using the multi-field irradiation 2500, described supra, allowingrepeated use of increased intensity at changing distal portions of thetumor 2120 as the patient 2130 is rotated in the multi-field irradiationsystem 2500.

As an example, the intensity controller subsystem 1940 adjusts theradio-frequency field in the RF cavity system 1910 to yield an intensityto correlate with radiation delivery efficiency and/or with theirradiation plan 1960. Preferably, the intensity controller subsystemadjusts the intensity of the radiation beam using a reading of theactual intensity of the proton beam 1950 or from the feedback currentfrom the extraction material 1930, which is proportional to theextracted beam intensity, as described supra. Thus, independent of thex- and y-axes targeting system and independent of the z-axis energy ofthe proton beam, the intensity of the proton beam is controlled,preferably in coordination with the multi-field irradiation system 2500,to yield peak intensities with greatest radiation delivery efficiency.The independent control of beam parameters allows use of a raster beamscanning system. Often, the greatest radiation delivery efficiencyoccurs, for a given rotational position of the patient, when the energyof the proton beam is largest. Hence, the intensity of the proton beamoptionally correlates with the energy of the proton beam. The system isoptionally timed with the patient's respiration cycle, as describedinfra. The system optionally operates in a raster beam scanning mode, asdescribed infra.

Proton Beam Position, Energy, and Intensity Control

An example of a proton scanning or targeting system 140 used to directthe protons to the tumor with 4-dimensional scanning control isprovided, where the 4-dimensional scanning control is along the x-, y-,and z-axes along with intensity control, as described supra. A fifthcontrollable axis is time. A sixth controllable axis is patientrotation. Typically, charged particles traveling along the transportpath 268 are directed through a first axis control element 142, such asa vertical control, and a second axis control element 144, such as ahorizontal control and into a tumor 2120. As described, supra, theextraction system also allows for simultaneous variation in the z-axis.Further, as described, supra, the intensity or dose of the extractedbeam is optionally simultaneously and independently controlled andvaried. Thus instead of irradiating a slice of the tumor, as in FIG.27A, all four dimensions defining the targeting spot of the protondelivery in the tumor are simultaneously variable. The simultaneousvariation of the proton delivery spot is illustrated in FIG. 27B by thespot delivery path 269 and in FIG. 28, where the intensity is controlledas a function of efficiency of radiation delivery.

In one example, the protons are initially directed around an outer edgeof the tumor and are then directed around an inner radius of the tumor.Combined with rotation of the subject about a vertical axis, amulti-field irradiation process is used where a not yet irradiatedportion of the tumor is preferably irradiated at the further distance ofthe tumor from the proton entry point into the body. This yields thegreatest percentage of the proton delivery, as defined by the Braggpeak, into the tumor and minimizes damage to peripheral healthy tissue.

Raster Scanning

Raster beam scanning is optionally used. In traditional spot targetingsystems, a spot of the tumor is targeted, then the radiation beam isturned off, a new spot is targeted, and the radiation beam is turned on.The cycle is repeated with changes in the x- and/or y-axis position. Instark contrast, in the raster beam scanning system, the proton beam isscanned from position to position in the tumor without turning off theradiation beam. In the raster scanning system, the irradiation is notnecessarily turned off between spots, rather the irradiation of thetumor is optionally continuous as the beam scans between 3-dimensionallocations in the tumor. The velocity of the scanning raster beam isoptionally independently controlled. Velocity is change in the x, y, zposition of the spot of the scanning beam with time. Hence, in avelocity control system, the rate of movement of the proton beam fromcoordinate to coordinate optionally varies with time or has amathematical change in velocity with time. Stated again, the movement ofthe spot of the scanning beam with time is optionally not constant as afunction of time. Further, the raster beam scanning system optionallyuses the simultaneous and/or independent control of the x- and/or y-axesposition, energy of the proton beam, intensity of the proton beam, androtational position of the patient using the acceleration, extractionsystems, and rotation systems, described supra.

In one example, a charged particle beam system for irradiation of atumor of a patient, includes: a synchrotron configured with anextraction foil, where a timing controller times the charged particlebeam striking the extraction foil in an acceleration period in thesynchrotron resulting in extraction of the charged particle beam at aselected energy and a raster beam scanning system configured to scan thecharged particle beam across delivery positions while both (1)constantly delivering the charged particle beam at and between thedelivery positions and (2) simultaneously varying the selected energylevel of the charged particle beam across the delivery positions.Preferably, an intensity controller is used that is configured tomeasure a current resulting from the charged particle beam striking theextraction foil, the current used as a feedback control to aradio-frequency cavity system, wherein an applied radio frequency, usingthe feedback control, in the radio-frequency cavity system controls thenumber of particles in the charged particle beam striking the extractionfoil resulting in intensity control of the charged particle beam.Preferably, a velocity controller is configured to change a rate ofmovement of the charged particle beam between the delivery positionalong x- and/or y-axes in the tumor as a function of time.

Imaging/X-Ray System

Herein, an X-ray system is used to illustrate an imaging system.

Timing

An X-ray is preferably collected either (1) just before or (2)concurrently with treating a subject with proton therapy for a couple ofreasons. First, movement of the body, described supra, changes the localposition of the tumor in the body relative to other body constituents.If the patient or subject 2130 has an X-ray taken and is then bodilymoved to a proton treatment room, accurate alignment of the proton beamto the tumor is problematic. Alignment of the proton beam to the tumor2120 using one or more X-rays is best performed at the time of protondelivery or in the seconds or minutes immediately prior to protondelivery and after the patient is placed into a therapeutic bodyposition, which is typically a fixed position or partially immobilizedposition. Second, the X-ray taken after positioning the patient is usedfor verification of proton beam alignment to a targeted position, suchas a tumor and/or internal organ position.

Positioning

An X-ray is preferably taken just before treating the subject to aid inpatient positioning. For positioning purposes, an X-ray of a large bodyarea is not needed. In one embodiment, an X-ray of only a local area iscollected. When collecting an X-ray, the X-ray has an X-ray path. Theproton beam has a proton beam path. Overlaying the X-ray path with theproton beam path is one method of aligning the proton beam to the tumor.However, this method involves putting the X-ray equipment into theproton beam path, taking the X-ray, and then moving the X-ray equipmentout of the beam path. This process takes time. The elapsed time whilethe X-ray equipment moves has a couple of detrimental effects. First,during the time required to move the X-ray equipment, the body moves.The resulting movement decreases precision and/or accuracy of subsequentproton beam alignment to the tumor. Second, the time required to movethe X-ray equipment is time that the proton beam therapy system is notin use, which decreases the total efficiency of the proton beam therapysystem.

X-Ray Source Lifetime

Preferably, components in the particle beam therapy system requireminimal or no maintenance over the lifetime of the particle beam therapysystem. For example, it is desirable to equip the proton beam therapysystem with an X-ray system having a long lifetime source, such as alifetime of about 20 years.

In one system, described infra, electrons are used to create X-rays. Theelectrons are generated at a cathode where the lifetime of the cathodeis temperature dependent. Analogous to a light bulb, where the filamentis kept in equilibrium, the cathode temperature is held in equilibriumat temperatures at about 200, 500, or 1000 degrees Celsius. Reduction ofthe cathode temperature results in increased lifetime of the cathode.Hence, the cathode used in generating the electrons is preferably heldat as low of a temperature as possible. However, if the temperature ofthe cathode is reduced, then electron emissions also decrease. Toovercome the need for more electrons at lower temperatures, a largecathode is used and the generated electrons are concentrated. Theprocess is analogous to compressing electrons in an electron gun;however, here the compression techniques are adapted to apply toenhancing an X-ray tube lifetime.

Referring now to FIG. 29, an example of an X-ray generation device 2900having an enhanced lifetime is provided. Electrons 2920 are generated ata cathode 2910, focused with a control electrode 2912, and acceleratedwith a series of accelerating electrodes 2940. The accelerated electrons2950 impact an X-ray generation source 2948 resulting in generatedX-rays that are then directed along an X-ray path 3070 to the subject2130. The concentrating of the electrons from a first diameter 2915 to asecond diameter 2916 allows the cathode to operate at a reducedtemperature and still yield the necessary amplified level of electronsat the X-ray generation source 2948. In one example, the X-raygeneration source 2948 is the anode coupled with the cathode 2910 and/orthe X-ray generation source is substantially composed of tungsten.

Still referring to FIG. 29, a more detailed description of an exemplaryX-ray generation device 2900 is described. An anode 2914/cathode 2910pair is used to generated electrons. The electrons 2920 are generated atthe cathode 2910 having a first diameter 2915, which is denoted d₁. Thecontrol electrodes 2912 attract the generated electrons 2920. Forexample, if the cathode is held at about −150 kV and the controlelectrode is held at about −149 kV, then the generated electrons 2920are attracted toward the control electrodes 2912 and focused. A seriesof accelerating electrodes 2940 are then used to accelerate theelectrons into a substantially parallel path 2950 with a smallerdiameter 2916, which is denoted d₂. For example, with the cathode heldat −150 kV, a first, second, third, and fourth accelerating electrodes2942, 2944, 2946, 2948 are held at about −120, −90, −60, and −30 kV,respectively. If a thinner body part is to be analyzed, then the cathode2910 is held at a smaller level, such as about −90 kV and the controlelectrode, first, second, third, and fourth electrode are each adjustedto lower levels. Generally, the voltage difference from the cathode tofourth electrode is less for a smaller negative voltage at the cathodeand vise-versa. The accelerated electrons 2950 are optionally passedthrough a magnetic lens 2960 for adjustment of beam size, such as acylindrical magnetic lens. The electrons are also optionally focusedusing quadrupole magnets 2970, which focus in one direction and defocusin another direction. The accelerated electrons 2950, which are nowadjusted in beam size and focused strike the X-ray generation source2948, such as tungsten, resulting in generated X-rays that pass throughan optional blocker 3062 and proceed along an X-ray path 3070 to thesubject. The X-ray generation source 2948 is optionally cooled with acooling element 2949, such as water touching or thermally connected to abackside of the X-ray generation source 2948. The concentrating of theelectrons from a first diameter 2915 to a second diameter 2916 allowsthe cathode to operate at a reduced temperature and still yield thenecessary amplified level of electrons at the X-ray generation source2948.

More generally, the X-ray generation device 2900 produces electronshaving initial vectors. One or more of the control electrode 2912,accelerating electrodes 2940, magnetic lens 2960, and quadrupole magnets2970 combine to alter the initial electron vectors into parallel vectorswith a decreased cross-sectional area having a substantially parallelpath, referred to as the accelerated electrons 2950. The process allowsthe X-ray generation device 2900 to operate at a lower temperature.Particularly, instead of using a cathode that is the size of theelectron beam needed, a larger electrode is used and the resultingelectrons 2920 are focused and/or concentrated into the requiredelectron beam needed. As lifetime is roughly an inverse of currentdensity, the concentration of the current density results in a largerlifetime of the X-ray generation device. A specific example is providedfor clarity. If the cathode has a fifteen mm radius or d₁ is about 30mm, then the area (π r²) is about 225 mm² times pi. If the concentrationof the electrons achieves a radius of five mm or d₂ is about 10 mm, thenthe area (π r²) is about 25 mm² times pi. The ratio of the two areas isabout nine (225π/25π). Thus, there is about nine times less density ofcurrent at the larger cathode compared to the traditional cathode havingan area of the desired electron beam. Hence, the lifetime of the largercathode approximates nine times the lifetime of the traditional cathode,though the actual current through the larger cathode and traditionalcathode is about the same. Preferably, the area of the cathode 2910 isabout 2, 4, 6, 8, 10, 15, 20, or 25 times that of the cross-sectionalarea of the substantially parallel electron beam 2950.

In another embodiment of the invention, the quadrupole magnets 2970result in an oblong cross-sectional shape of the electron beam 2950. Aprojection of the oblong cross-sectional shape of the electron beam 2950onto the X-ray generation source 2948 results in an X-ray beam 3070 thathas a small spot in cross-sectional view, which is preferablysubstantially circular in cross-sectional shape, that is then passedthrough the patient 2930. The small spot is used to yield an X-rayhaving enhanced resolution at the patient.

Referring now to FIG. 30, in one embodiment, an X-ray is generated closeto, but not in, the proton beam path. A proton beam therapy system andan X-ray system combination 3000 is illustrated in FIG. 30. The protonbeam therapy system has a proton beam 268 in a transport system afterthe Lamberson extraction magnet 292 of the synchrotron 130. The protonbeam is directed by the scanning/targeting/delivery system 140 to atumor 2120 of a patient 2130. The X-ray system 3005 includes an electronbeam source 2905 generating an electron beam 2950. The electron beam isdirected to an X-ray generation source 2948, such as a piece oftungsten. Preferably, the tungsten X-ray source is located about 1, 2,3, 5, 10, 15, or 20 millimeters from the proton beam path 268. When theelectron beam 2950 hits the tungsten, X-rays are generated in alldirections. X-rays are blocked with a port 3062 and are selected for anX-ray beam path 3070. The X-ray beam path 3070 and proton beam path 268run substantially in parallel as they progress to the tumor 2120. Thedistance between the X-ray beam path 3070 and proton beam path 269preferably diminishes to near zero and/or the X-ray beam path 3070 andproton beam path 269 overlap by the time they reach the tumor 2120.Simple geometry shows this to be the case given the long distance, of atleast a meter, between the tungsten and the tumor 2120. The distance isillustrated as a gap 3080 in FIG. 30. The X-rays are detected at anX-ray detector 3090, which is used to form an image of the tumor 2120and/or position of the patient 2130.

As a whole, the system generates an X-ray beam that lies insubstantially the same path as the proton therapy beam. The X-ray beamis generated by striking a tungsten or equivalent material with anelectron beam. The X-ray generation source is located proximate to theproton beam path. Geometry of the incident electrons, geometry of theX-ray generation material, and/or geometry of the X-ray beam blocker 262yield an X-ray beam that runs either substantially in parallel with theproton beam or results in an X-ray beam path that starts proximate theproton beam path an expands to cover and transmit through a tumorcross-sectional area to strike an X-ray detector array or film allowingimaging of the tumor from a direction and alignment of the protontherapy beam. The X-ray image is then used to control the chargedparticle beam path to accurately and precisely target the tumor, and/oris used in system verification and validation.

Referring now to FIG. 31, additional geometry of the electron beam path2950 and X-ray beam path 3070 is illustrated. Particularly, the electronbeam 2950 is shown as an expanded electron beam path 2952, 2954. Also,the X-ray beam path 3070 is shown as an expanded X-ray beam path 3072,3074.

Referring now to FIG. 32, a 3-dimensional (3-D) X-ray tomography system3200 is presented. In a typical X-ray tomography system, the X-raysource and detector rotationally translate about a stationary subject.In the X-ray tomography system described herein, the X-ray source anddetector are stationary and the patient 2130 rotates. The stationaryX-ray source allows a system where the X-ray source 2948 is proximatethe proton therapy beam path 268, as described supra. In addition, therotation of the patient 2130 allows the proton dosage to be distributedaround the body, rather than being concentrated on one static entranceside of the body. Further, the 3-D X-ray tomography system allows forsimultaneous updates of the tumor position relative to body constituentsin real-time during proton therapy treatment of the tumor 2120 in thepatient 2130. The X-ray tomography system is further described, infra.

Patient Imaging with Rotation

In a first step of the X-ray tomography system 3200, the patient 2130 ispositioned relative to the X-ray beam path 3070 and proton beam path 268using a patient semi-immobilization/placement system, described infra.After patient 2130 positioning, a series of reference 2-D X-ray imagesare collected, on a detector array 3090 or film, of the patient 2130 andtumor 2120 as the subject is rotated about a y-axis 2117. For example, aseries of about 50, 100, 200, or 400 X-ray images of the patient arecollected as the patient is rotated. In a second example, an X-ray imageis collected with each n degrees of rotation of the patient 2130, wheren is about ½, 1, 2, 3, 5, 10, or 20 degrees of rotation. Preferably,about 200 images are collected during one full rotation of the patientthrough 360 degrees. Subsequently, using the reference 2-D X-ray images,an algorithm produces a reference 3-D picture of the tumor 2120 relativeto the patient's constituent body parts. A tumor 2120 irradiation planis made using the 3-D picture of the tumor 2120 and the patient'sconstituent body parts. Creation of the proton irradiation plan isoptionally performed after the patient has moved from the X-ray imagingarea.

In a second step, the patient 2130 is repositioned relative to the X-raybeam path 3070 and proton beam path 268 using the patientsemi-immobilization/placement system. Just prior to implementation ofthe proton irradiation plan, a few comparative X-ray images of thepatient 2130 and tumor 2120 are collected at a limited number ofpositions using the X-ray tomography system 2600 setup. For example, asingle X-ray image is collected with the patient positioned straight on,at angles of plus/minus forty-five degrees, and/or at angles ofplus/minus ninety degrees relative to the proton beam path 268. Theactual orientation of the patient 2130 relative to the proton beam path268 is optionally any orientation. The actual number of comparativeX-ray images is also optionally any number of images, though thepreferable number of comparative X-ray images is about 2 to 5comparative images. The comparative X-ray images are compared to thereference X-ray images and differences are detected. A medical expert oran algorithm determines if the difference between the reference imagesand the comparative images is significant. Based upon the differences,the medical expert or algorithm determines if: proton treatment shouldcommence, be halted, or adapted in real-time. For example, ifsignificant differences in the X-ray images are observed, then thetreatment is preferably halted and the process of collecting a reference3-D picture of the patient's tumor is reinitiated. In a second example,if the differences in the X-ray images are observed to be small, thenthe proton irradiation plan commences. In a third example, the algorithmor medical expert can adapt the proton irradiation plan in real-time toadjust for differences in tumor location resulting from changes inposition of the tumor 2120 in the patient 2130 or from differences inthe patient 2130 placement. In the third example, the adaptive protontherapy increases patient throughput and enhances precision and accuracyof proton irradiation of the tumor 2120 relative to the healthy tissueof the patient 2130.

Patient Immobilization

Accurate and precise delivery of a proton beam to a tumor of a patientrequires: (1) positioning control of the proton beam and (2) positioningcontrol of the patient. As described, supra, the proton beam iscontrolled using algorithms and magnetic fields to a diameter of about0.5, 1, or 2 millimeters. This section addresses partial immobilization,restraint, and/or alignment of the patient to insure the tightlycontrolled proton beam efficiently hits a target tumor and notsurrounding healthy tissue as a result of patient movement.

Herein, an x-, y-, and z-axes coordinate system and rotation axis isused to describe the orientation of the patient relative to the protonbeam. The z-axis represent travel of the proton beam, such as the depthof the proton beam into the patient. When looking at the patient downthe z-axis of travel of the proton beam, the x-axis refers to movingleft or right across the patient and the y-axis refers to movement up ordown the patient. A first rotation axis is rotation of the patient aboutthe y-axis and is referred to herein as a rotation axis, bottom unit2112 rotation axis, or y-axis of rotation 2117. In addition, tilt isrotation about the x-axis, yaw is rotation about the y-axis, and roll isrotation about the z-axis. In this coordinate system, the proton beampath 269 optionally runs in any direction. As an illustrative matter,the proton beam path running through a treatment room is described asrunning horizontally through the treatment room.

In this section, three examples of positioning systems are provided: (1)a semi-vertical partial immobilization system 3300; (2) a sittingpartial immobilization system 3400; and (3) a laying position 3500.Elements described for one immobilization system apply to otherimmobilization systems with small changes. For example, a headrest, ahead support, or head restraint will adjust along one axis for areclined position, along a second axis for a seated position, and alonga third axis for a laying position. However, the headrest itself issimilar for each immobilization position.

Vertical Patient Positioning/Immobilization

Referring now to FIG. 33, the semi-vertical patient positioning system3300 is preferably used in conjunction with proton therapy of tumors inthe torso. The patient positioning and/or immobilization system controlsand/or restricts movement of the patient during proton beam therapy. Ina first partial immobilization embodiment, the patient is positioned ina semi-vertical position in a proton beam therapy system. Asillustrated, the patient is reclining at an angle alpha, α, about 45degrees off of the y-axis as defined by an axis running from head tofoot of the patient. More generally, the patient is optionallycompletely standing in a vertical position of zero degrees off the ofy-axis or is in a semi-vertical position alpha that is reclined about 5,10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, or 65 degrees off of they-axis toward the z-axis.

Patient positioning constraints 3315 that are used to maintain thepatient in a treatment position, include one or more of: a seat support3320, a back support 3330, a head support 3340, an arm support 3350, aknee support 3360, and a foot support 3370. The constraints areoptionally and independently rigid or semi-rigid. Examples of asemi-rigid material include a high or low density foam or avisco-elastic foam. For example the foot support is preferably rigid andthe back support is preferably semi-rigid, such as a high density foammaterial. One or more of the positioning constraints 3315 are movableand/or under computer control for rapid positioning and/orimmobilization of the patient. For example, the seat support 3320 isadjustable along a seat adjustment axis 3322, which is preferably they-axis; the back support 3330 is adjustable along a back support axis3332, which is preferably dominated by z-axis movement with a y-axiselement; the head support 3340 is adjustable along a head support axis3342, which is preferably dominated by z-axis movement with a y-axiselement; the arm support 3350 is adjustable along an arm support axis3352, which is preferably dominated by z-axis movement with a y-axiselement; the knee support 3360 is adjustable along a knee support axis3362, which is preferably dominated by z-axis movement with a y-axiselement; and the foot support 3370 is adjustable along a foot supportaxis 3372, which is preferably dominated by y-axis movement with az-axis element.

If the patient is not facing the incoming proton beam, then thedescription of movements of support elements along the axes change, butthe immobilization elements are the same.

An optional camera 3380 is used with the patient immobilization system.The camera views the patient/subject 2130 creating a video image. Theimage is provided to one or more operators of the charged particle beamsystem and allows the operators a safety mechanism for determining ifthe subject has moved or desires to terminate the proton therapytreatment procedure. Based on the video image, the operators optionallysuspend or terminate the proton therapy procedure. For example, if theoperator observes via the video image that the subject is moving, thenthe operator has the option to terminate or suspend the proton therapyprocedure.

An optional video display or display monitor 3390 is provided to thepatient. The video display optionally presents to the patient any of:operator instructions, system instructions, status of treatment, orentertainment.

Motors for positioning the patient positioning constraints 3315, thecamera 3380, and/or video display 3390 are preferably mounted above orbelow the proton transport path 268 or momentary proton scanning path269.

Respiration control is optionally performed by using the video display.As the patient breathes, internal and external structures of the bodymove in both absolute terms and in relative terms. For example, theoutside of the chest cavity and internal organs both have absolute moveswith a breath. In addition, the relative position of an internal organrelative to another body component, such as an outer region of the body,a bone, support structure, or another organ, moves with each breath.Hence, for more accurate and precise tumor targeting, the proton beam ispreferably delivered at a point in time where the position of theinternal structure or tumor is well defined, such as at the bottom ortop of each breath. The video display is used to help coordinate theproton beam delivery with the patient's respiration cycle. For example,the video display optionally displays to the patient a command, such asa hold breath statement, a breathe statement, a countdown indicatingwhen a breath will next need to be held, or a countdown until breathingmay resume.

Sitting Patient Positioning/Immobilization

In a second partial immobilization embodiment, the patient is partiallyrestrained in a seated position 3400. The sitting restraint system usessupport structures similar to the support structures in thesemi-vertical positioning system, described supra, with an exceptionthat the seat support is replaced by a chair and the knee support is notrequired. The seated restraint system generally retains the adjustablesupport, rotation about the y-axis, camera, video, and breath controlparameters described in the semi-vertical embodiment, described supra.

Referring now to FIG. 34, a particular example of a sitting patientsemi-immobilization system 3400 is provided. The sitting system ispreferably used for treatment of head and/or neck tumors. Asillustrated, the patient is positioned in a seated position on a chair3410 for particle therapy. The patient is further immobilized using anyof the: the head support 3340, the back support 3330, the hand support3350, the knee support 3360, and the foot support 3370. The supports3320, 3330, 3340, 3350, 3360, 3370 preferably have respective axes ofadjustment 3322, 3332, 3342, 3352, 3362, 3372 as illustrated. The chair3410 is either readily removed to allow for use of a different patientconstraint system or adapts under computer control to a new patientposition, such as the semi-vertical system.

Laying Patient Positioning/Immobilization

In a third partial immobilization embodiment, the patient is partiallyrestrained in a laying position. Referring now to FIG. 34, the layingrestraint system 3500 has support structures that are similar to thesupport structures used in the sitting positioning system 3400 andsemi-vertical positioning system 3300, described supra. In the layingposition, optional restraint, support, or partial immobilizationelements include one or more of: the head support 3340 and the backsupport, hip, and shoulder 3330 support. The supports preferably haverespective axes of adjustment that are rotated as appropriate for alaying position of the patient. The laying position restraint systemgenerally retains the adjustable supports, rotation about the y-axis,camera, video, and breath control parameters described in thesemi-vertical embodiment, described supra.

If the patient is very sick, such as the patient has trouble standingfor a period of about one to three minutes required for treatment, thenbeing in a partially supported system can result in some movement of thepatient due to muscle strain. In this and similar situations, treatmentof a patient in a laying position on a support table 3520 ispreferentially used. The support table has a horizontal platform tosupport the bulk of the weight of the patient. Preferably, thehorizontal platform is detachable from a treatment platform. In a layingpositioning system 3500, the patient is positioned on a platform 3510,which has a substantially horizontal portion for supporting the weightof the body in a horizontal position. Optional hand grips are used,described infra. In one embodiment, the platform 3510 affixes relativeto the table 3520 using a mechanical stop or lock element 3530 andmatching key element 3535 and/or the patient 2130 is aligned orpositioned relative to a placement element 3560.

Additionally, upper leg support 3544, lower leg support 3540, and/or armsupport 3550 elements are optionally added to raise, respectively, anarm or leg out of the proton beam path 269 for treatment of a tumor inthe torso or to move an arm or leg into the proton beam path 269 fortreatment of a tumor in the arm or leg. This increases proton deliveryefficiency, as described supra. The leg supports 3540, 3544 and armsupport 3550 are each optionally adjustable along support axes or arcs3542, 3546, 3552. One or more leg support elements are optionallyadjustable along an arc to position the leg into the proton beam path269 or to remove the leg from the proton beam path 269, as describedinfra. An arm support element is preferably adjustable along at leastone arm adjustment axis or along an arc to position the arm into theproton beam path 269 or to remove the arm from the proton beam path 269,as described infra.

Preferably, the patient is positioned on the platform 3510 in an area orroom outside of the proton beam path 268 and is wheeled or slid into thetreatment room or proton beam path area. For example, the patient iswheeled into the treatment room on a gurney where the top of the gurney,which is the platform, detaches and is positioned onto a table. Theplatform is preferably lifted onto the table or slid onto the table sothat the gurney or bed need not be lifted onto the table.

The semi-vertical patient positioning system 3300 and sitting patientpositioning system 3400 are preferentially used to treatment of tumorsin the head or torso due to efficiency. The semi-vertical patientpositioning system 3300, sitting patient positioning system 3400, andlaying patient positioning system 3500 are all usable for treatment oftumors in the patient's limbs.

Support System Elements

Positioning constraints 3315 include all elements used to position thepatient, such as those described in the semi-vertical positioning system3300, sitting positioning system 3400, and laying positioning system3500. Preferably, positioning constraints or support system elements arealigned in positions that do not impede or overlap the proton beam path269. However, in some instances the positioning constraints are in theproton beam path 269 during at least part of the time of treatment ofthe patient. For instance, a positioning constraint element may residein the proton beam path 269 during part of a time period where thepatient is rotated about the y-axis during treatment. In cases or timeperiods that the positioning constraints or support system elements arein the proton beam path, then an upward adjustment of proton beam energyis preferably applied that increases the proton beam energy to offsetthe positioning constraint element impedance of the proton beam. Thistime period and energy is a function of rotational orientation of thepatient. In one case, the proton beam energy is increased by a separatemeasure of the positioning constraint element impedance determinedduring a reference scan of the positioning constraint system element orset of reference scans of the positioning constraint element as afunction of rotation about the y-axis.

For clarity, the positioning constraints 3315 or support system elementsare herein described relative to the semi-vertical positioning system3300; however, the positioning elements and descriptive x-, y-, andz-axes are adjustable to fit any coordinate system, to the sittingpositioning system 3400, or the laying positioning system 3500.

An example of a head support system is described to support, align,and/or restrict movement of a human head. The head support systempreferably has several head support elements including any of: a back ofhead support, a right of head alignment element, and a left of headalignment element. The back of head support element is preferably curvedto fit the head and is optionally adjustable along a head support axis,such as along the z-axis. Further, the head supports, like the otherpatient positioning constraints, is preferably made of a semi-rigidmaterial, such as a low or high density foam, and has an optionalcovering, such as a plastic or leather. The right of head alignmentelement and left of head alignment elements or head alignment elements,are primarily used to semi-constrain movement of the head or to fullyimmobilize the head. The head alignment elements are preferably paddedand flat, but optionally have a radius of curvature to fit the side ofthe head. The right and left head alignment elements are preferablyrespectively movable along translation axes to make contact with thesides of the head. Restricted movement of the head during proton therapyis important when targeting and treating tumors in the head or neck. Thehead alignment elements and the back of head support element combine torestrict tilt, rotation or yaw, roll and/or position of the head in thex-, y-, z-axes coordinate system.

Referring now to FIG. 36 another example of a head support system 3600is described for positioning and/or restricting movement of a human head2102 during proton therapy of a solid tumor in the head or neck. In thissystem, the head is restrained using 1, 2, 3, 4, or more straps orbelts, which are preferably connected or replaceably connected to a backof head support element 3610. In the example illustrated, a first strap3620 pulls or positions the forehead to the head support element 3610,such as by running predominantly along the z-axis. Preferably a secondstrap 3630 works in conjunction with the first strap 3620 to prevent thehead from undergoing tilt, yaw, roll or moving in terms of translationalmovement on the x-, y-, and z-axes coordinate system. The second strap3630 is preferably attached or replaceable attached to the first strap3620 at or about: (1) a forehead position 3632; (2) at a position on oneor both sides of the head 3634; and/or (3) at or about a position on thesupport element 3636. A third strap 3640 preferably orientates the chinof the subject relative to the support element 3610 by runningdominantly along the z-axis. A fourth strap 3650 preferably runs along apredominantly y- and z-axes to hold the chin relative to the headsupport element 3610 and/or proton beam path. The third 3640 strappreferably is attached to or is replaceably attached to the fourth strap3650 during use at or about the patient's chin position 3642. The secondstrap 3630 optionally connects 3636 to the fourth strap 3650 at or aboutthe support element 3610. The four straps 3620, 3630, 3640, 3650 areillustrative in pathway and interconnection. Any of the strapsoptionally hold the head along different paths around the head andconnect to each other in separate fashion. Naturally, a given strappreferably runs around the head and not just on one side of the head.Any of the straps 3620, 3630, 3640, and 3650 are optionally usedindependently or in combinations and permutations with the other straps.The straps are optionally indirectly connected to each other via asupport element, such as the head support element 3610. The straps areoptionally attached to the head support element 3610 using hook and looptechnology, a buckle, or fastener. Generally, the straps combine tocontrol position, front-to-back movement of the head, side-to-sidemovement of the head, tilt, yaw, roll, and/or translational position ofthe head.

The straps are preferably of known impedence to proton transmissionallowing a calculation of peak energy release along the z-axis to becalculated. For example, adjustment to the Bragg peak energy is madebased on the slowing tendency of the straps to proton transport.

Referring now to FIG. 37, still another example of a head support system3340 is described. The head support 3340 is preferably curved to fit astandard or child sized head. The head support 3340 is optionallyadjustable along a head support axis 3342. Further, the head supports,like the other patient positioning constraints, is preferably made of asemi-rigid material, such as a low or high density foam, and has anoptional covering, such as a plastic or leather.

Elements of the above described head support, head positioning, and headimmobilization systems are optionally used separately or in combination.

Still referring to FIG. 37, an example of the arm support 3350 isfurther described. The arm support preferably has a left hand grip 3710and a right hand grip 3720 used for aligning the upper body of thepatient 2130 through the action of the patient 2130 gripping the leftand right hand grips 3710, 3720 with the patient's hands 2134. The leftand right hand grips 3710, 3720 are preferably connected to the armsupport 3350 that supports the mass of the patient's arms. The left andright hand grips 3710, 3720 are preferably constructed using asemi-rigid material. The left and right hand grips 3710, 3720 areoptionally molded to the patient's hands to aid in alignment. The leftand right hand grips optionally have electrodes, as described supra.

Patient Respiration Monitoring

Preferably, the patient's respiration pattern is monitored. When asubject or patient 2130 is breathing many portions of the body move witheach breath. For example, when a subject breathes the lungs move as dorelative positions of organs within the body, such as the stomach,kidneys, liver, chest muscles, skin, heart, and lungs. Generally, mostor all parts of the torso move with each breath. Indeed, the inventorshave recognized that in addition to motion of the torso with eachbreath, various motion also exists in the head and limbs with eachbreath. Motion is to be considered in delivery of a proton dose to thebody as the protons are preferentially delivered to the tumor and not tosurrounding tissue. Motion thus results in an ambiguity in where thetumor resides relative to the beam path. To partially overcome thisconcern, protons are preferentially delivered at the same point in eachof a series of respiration cycles.

Initially a rhythmic pattern of breathing of a subject is determined.The cycle is observed or measured. For example, an X-ray beam operatoror proton beam operator can observe when a subject is breathing or isbetween breaths and can time the delivery of the protons to a givenperiod of each breath. Alternatively, the subject is told to inhale,exhale, and/or hold their breath and the protons are delivered duringthe commanded time period.

Preferably, one or more sensors are used to determine the respirationcycle of the individual. Two examples of a respiration monitoring system4010 are provided: (1) a thermal monitoring system and (2) a forcemonitoring system.

Referring again to FIG. 35, a first example of the thermal respirationmonitoring system is provided. In the thermal respiration monitoringsystem, a sensor is placed by the nose and/or mouth of the patient. Asthe jaw of the patient is optionally constrained, as described supra,the thermal respiration monitoring system is preferably placed by thepatient's nose exhalation path. To avoid steric interference of thethermal sensor system components with proton therapy, the thermalrespiration monitoring system is preferably used when treating a tumornot located in the head or neck, such as a when treating a tumor in thetorso or limbs. In the thermal monitoring system, a first thermalresistor 3670 is used to monitor the patient's respiration cycle and/orlocation in the patient's respiration cycle. Preferably, the firstthermal resistor 3670 is placed by the patient's nose, such that thepatient exhaling through their nose onto the first thermal resistor 3670warms the first thermal resistor 3670 indicating an exhale. Preferably,a second thermal resistor 3660 operates as an environmental temperaturesensor. The second thermal resistor 3660 is preferably placed out of theexhalation path of the patient but in the same local room environment asthe first thermal resistor 3670. Generated signal, such as current fromthe thermal resistors 3670, 3660, is preferably converted to voltage andcommunicated with the main controller 110 or a sub-controller of themain controller. Preferably, the second thermal resistor 3660 is used toadjust for the environmental temperature fluctuation that is part of asignal of the first thermal resistor 3670, such as by calculating adifference between the values of the thermal resistors 3670, 3660 toyield a more accurate reading of the patient's respiration cycle.

Referring again to FIG. 34, a second example of a monitoring system isprovided. In an example of a force respiration monitoring system, asensor is placed by the torso. To avoid steric interference of the forcesensor system components with proton therapy, the force respirationmonitoring system is preferably used when treating a tumor located inthe head, neck, or limbs. In the force monitoring system, a belt orstrap 3450 is placed around an area of the patient's torso that expandsand contracts with each respiration cycle of the patient. The belt 3450is preferably tight about the patient's chest and is flexible. A forcemeter 3452 is attached to the belt and senses the patients respirationpattern. The forces applied to the force meter 3452 correlate withperiods of the respiration cycle. The signals from the force meter 3452are preferably communicated with the main controller 110 or asub-controller of the main controller.

Coordinated Charged Particle Beam Control

In this section, charged particle beam control systems, described supra,are coordinated for cancer therapy.

Positioning, Imaging, and Irradiation

Referring now to FIG. 38, a method of cancer therapy is provided. Inthis method, the patient is first positioned 3810, then the tumor isimaged 3820, subsequently a charged particle irradiation plan isdeveloped 3830, and then the charged particle irradiation plan isimplemented 3840. Further examples of the steps provided in FIG. 38 aredescribed, infra, along with additional optional steps. For example, thepositioning, imaging, and irradiation steps are optionally integratedwith patient translation control, patient rotation control, and/orpatient respiration control. Additionally, any of the steps describedherein are optionally coordinated with charged particle beam generation,acceleration, extraction, and/or delivery. Additionally, any of thesteps are optionally coordinated with x-, y-axis beam trajectorycontrol, delivered energy control, delivered intensity control, timingof charged particle delivery, and/or distribution of radiation strikinghealthy tissue.

Tumor Imaging

Referring now to FIG. 39, a method of tumor imaging is provided. In afirst step, the patient is positioned 3810, such as with the patientimmobilization and/or positioning systems described supra. Subsequently,the tumor is imaged 3820, such as with the imaging/X-ray systemdescribed supra. Preferably, each image is a 2-dimensional image. If theimage is not complete 3910, then the patient is rotated 3920, such aswith the multi-field irradiation rotatable platform described supra. Forinstance, the image is collected with rotation of the patient about they-axis 2117. After rotation of n degrees of rotation of the patient2130, where n is about ½, 1, 2, 3, 5, 10, or 20 degrees, another imageis collected 3820. The imaging 3820 and rotation 3920 processes arerepeated until the tumor 2120 is suitably imaged. A 3-dimensional imageis created 3930 using the two-dimensional images collected as a functionof patient rotation.

Respiration Control

Referring now to FIG. 40, a patient is positioned 3810 and once therhythmic pattern of the subject's breathing or respiration cycle isdetermined 4010, a signal is optionally delivered to the patient, suchas via the display monitor 3390, to more precisely control the breathingfrequency 4020. For example, the display screen 3390 is placed in frontof the patient and a message or signal is transmitted to the displayscreen 3390 directing the subject when to hold their breath and when tobreathe. Typically, a respiration control module uses input from one ormore of the respiration sensors. For example, the input is used todetermine when the next breath exhale is to complete. At the bottom ofthe breath, the control module displays a hold breath signal to thesubject, such as on a monitor, via an oral signal, digitized andautomatically generated voice command, or via a visual control signal.Preferably, a display monitor 3390 is positioned in front of the subjectand the display monitor displays breathing commands to the subject.Typically, the subject is directed to hold their breath for a shortperiod of time, such as about ½, 1, 2, 3, 5, or 10 seconds. The periodof time the breath is held is preferably synchronized to the deliverytime of the proton beam to the tumor, which is about ½, 1, 2, or 3seconds. While delivery of the protons at the bottom of the breath ispreferred, protons are optionally delivered at any point in therespiration cycle, such as upon full inhalation. Delivery at the top ofthe breath or when the patient is directed to inhale deeply and holdtheir breath by the respiration control module is optionally performedas at the top of the breath the chest cavity is largest and for sometumors the distance between the tumor and surrounding tissue ismaximized or the surrounding tissue is rarefied as a result of theincreased volume. Hence, protons hitting surrounding tissue isminimized. Optionally, the display screen tells the subject when theyare about to be asked to hold their breath, such as with a 3, 2, 1,second countdown so that the subject is aware of the task they are aboutto be asked to perform.

X-Ray Synchronization with Patient Respiration

In one embodiment, X-ray images are collected in synchronization withpatient respiration. The synchronization enhances X-ray image clarity byremoving position ambiguity due to the relative movement of bodyconstituents during a patient respiration cycle.

In a second embodiment, an X-ray system is orientated to provide X-rayimages of a patient in the same orientation as viewed by a protontherapy beam, is synchronized with patient respiration, is operable on apatient positioned for proton therapy, and does not interfere with aproton beam treatment path. Preferably, the synchronized system is usedin conjunction with a negative ion beam source, synchrotron, and/ortargeting method and apparatus to provide an X-ray timed with patientrespiration. Preferably, X-ray images are collected immediately prior toand/or concurrently with particle beam therapy irradiation to ensuretargeted and controlled delivery of energy relative to a patientposition resulting in efficient, precise, and/or accurate in-vivotreatment of a solid cancerous tumor with minimization of damage tosurrounding healthy tissue.

An X-ray delivery control algorithm is used to synchronize delivery ofthe X-rays to the patient 2130 within a given period of each breath,such as at the top or bottom of a breath, and/or when the subject isholding their breath. For clarity of combined X-ray images, the patientis preferably both accurately positioned and precisely aligned relativeto the X-ray beam path 3070. The X-ray delivery control algorithm ispreferably integrated with the respiration control module. Thus, theX-ray delivery control algorithm knows when the subject is breathing,where in the respiration cycle the subject is, and/or when the subjectis holding their breath. In this manner, the X-ray delivery controlalgorithm delivers X-rays at a selected period of the respiration cycle.Accuracy and precision of patient alignment allow for (1) more accurateand precise location of the tumor 2120 relative to other bodyconstituents and (2) more accurate and precise combination of X-rays ingeneration of a 3-dimensional X-ray image of the patient 2130 and tumor2120.

Referring again to FIG. 40, an example of generating an X-ray image ofthe patient 2130 and tumor 2120 using the X-ray generation device 3000or 3-dimensional X-ray generation device 3000 as a known function oftime of the patient's respiration cycle is provided. In one embodiment,as a first step the main controller 110 instructs, monitors, and/or isinformed of patient positioning 3810. In a first example of patientpositioning 3810, the automated patient positioning system, describedsupra, under main controller 110 control, is used to align the patient2130 relative to the X-ray beam path 3070. In a second example ofpatient positioning, the main controller 110 is told via sensors orhuman input that the patient 2130 is aligned. In a second step, patientrespiration is then monitored 4010, as described infra. As a firstexample of respiration monitoring, an X-ray is collected 4030 at a knownpoint in the patient respiration cycle. In a second example ofrespiration monitoring, the patient's respiration cycle is firstcontrolled in a third step of controlling patient respiration 4020 andthen as a fourth step an X-ray is collected 4030 at a controlled pointin the patient respiration cycle. Preferably, the cycle of patientpositioning 3810, patient respiration monitoring 4010, patientrespiration control 4020, and collecting an X-ray 4030 is repeated withdifferent patient positions. For example, the patient 2130 is rotatedabout an axis 2117 and X-rays are collected as a function of therotation. In a fifth step, a 3-dimensional X-ray image 4040 is generatedof the patient 2130, tumor 2120, and body constituents about the tumorusing the collected X-ray images, such as with the 3-dimensional X-raygeneration device 3000, described supra. The patient respirationmonitoring and control steps are further described, infra.

An X-ray timed with patient respiration where the X-ray is preferablycollected immediately prior to and/or concurrently with particle beamtherapy irradiation to ensure targeted and controlled delivery of energyrelative to a patient position resulting in efficient, precise, and/oraccurate treatment of a solid cancerous tumor with minimization ofdamage to surrounding healthy tissue in a patient using the proton beamposition verification system.

Proton Beam Therapy Synchronization with Respiration

In one embodiment, charged particle therapy and preferably multi-fieldproton therapy is coordinated and synchronized with patient respirationvia use of the respiration feedback sensors, described supra, used tomonitor and/or control patient respiration. Preferably, the chargedparticle therapy is performed on a patient in a partially immobilizedand repositionable position and the proton delivery to the tumor 2120 istimed to patient respiration via control of charged particle beaminjection, acceleration, extraction, and/or targeting methods andapparatus. The synchronization enhances proton delivery accuracy byremoving position ambiguity due to the relative movement of bodyconstituents during a patient respiration cycle. Synchrotron control todeliver protons at a desired point in the respiration cycle is describedinfra.

In a second embodiment, the X-ray system, described supra, is used toprovide X-ray images of a patient in the same orientation as viewed by aproton therapy beam and both the X-ray system and the proton therapybeam are synchronized with patient respiration. Again, synchrotroncontrol to deliver protons at a desired point in the respiration cycleis described infra.

A proton delivery control algorithm is used to synchronize delivery ofthe protons to the tumor within a given period of each breath, such asat the top of a breath, at the bottom of a breath, and/or when thesubject is holding their breath. The proton delivery control algorithmis preferably integrated with the respiration control module. Thus, theproton delivery control algorithm knows when the subject is breathing,where in the respiration cycle the subject is, and/or when the subjectis holding their breath. The proton delivery control algorithm controlswhen protons are injected and/or inflected into the synchrotron, when anRF signal is applied to induce an oscillation, as described supra, andwhen a DC voltage is applied to extract protons from the synchrotron, asdescribed supra. Typically, the proton delivery control algorithminitiates proton inflection and subsequent RF induced oscillation beforethe subject is directed to hold their breath or before the identifiedperiod of the respiration cycle selected for a proton delivery time. Inthis manner, the proton delivery control algorithm delivers protons at aselected period of the respiration cycle by simultaneously or nearlysimultaneously delivering the high DC voltage to the second pair ofplates, described supra, which results in extraction of the protons fromthe synchrotron and subsequent delivery to the subject at the selectedtime point. Since the period of acceleration of protons in thesynchrotron is constant or known for a desired energy level of theproton beam, the proton delivery control algorithm is used to set an ACRF signal that matches the respiration cycle or directed respirationcycle of the subject.

The above described charged particle therapy elements are combined incombinations and/or permutations in developing and implementing a tumortreatment plan, described infra.

Proton Beam Generation, Injection, Acceleration, Extraction, andDelivery

Referring now to FIG. 41, an example of implementation of theirradiation plan 3840 is provided. The multi-axis and/or multi-fieldcharged particle cancer therapy system elements described herein arepreferably coordinated with charged particle delivery 4100. Afterpatient positioning 3810 and reading the irradiation plan instructions4110, hydrogen is injected 4115 into the negative ion source 310, plasmais generated 4120, a negative ion is extracted 4125, and the negativeion is accelerated 4130, converted into a positive ion 4140, andinjected into the synchrotron 4145. Subsequently, the positive ion isaccelerated 4150, extraction is initiated 4155, intensity of theirradiation beam is controlled 4160, extraction of the charged particlebeam is performed 4165, and the tumor is irradiated 4170. Preferably,one or more elements of the charged particle delivery 4100 system aretimed with patient respiration. After tumor irradiation 4170, thepatient is preferably rotated 3920 and the irradiation sequence isrepeated yielding multi-field irradiation of the tumor 2120. The entiresequence is optionally performed using the intensity modulated3-dimensional scanning system 2800, described supra.

Multi-Axis Charged Particle Irradiation

Referring now to FIG. 42, another example of implementation of theirradiation plan 3840 is provided. In this example, a multi-axis chargedparticle beam therapy system is provided, where multi-axis refers toindependent control of: x-axis beam control, y-axis beam control,delivered beam energy, and/or delivered beam intensity. The multi-axiscontrol is preferably implemented with multi-field charge particleirradiation, such as via use of independent control of rotation and/ortranslation of the patient. In this example, the main controller 110independently adjusts x-axis targeting of the proton beam 4210, y-axistargeting of the proton beam 4220, rotational position of the patient4230, delivered energy of the proton beam 4240, and/or deliveredintensity of the proton beam in the step of irradiating the tumor 3840.The process is optionally repeated or iterated using a continuouslyirradiating and scanning charged particle irradiation system asdescribed using the 3-dimensional scanning system 2800.

Developing and Implementing a Tumor Irradiation Plan

A series of steps are performed to design and execute a radiationtreatment plan for treating a tumor 2120 in a patient 2130. The stepsinclude one or more of:

-   -   positioning and immobilizing the patient;    -   recording the patient position;    -   monitoring patient respiration;    -   controlling patient respiration;    -   collecting multi-field images of the patient to determine tumor        location relative to body constituents;    -   developing a radiation treatment plan;    -   repositioning the patient;    -   verifying tumor location; and    -   irradiating the tumor.

In this section, an overview of developing the irradiation plan andsubsequent implementation of the irradiation plan is initiallypresented, the individual steps are further described, and a moredetailed example of the process is then described.

Referring now to FIG. 43, an overview of a system for development of anirradiation plan and subsequent implementation of the irradiation plan4300 is provided. Preferably, all elements of the positioning,respiration monitoring, imaging, and tumor irradiation system 4300 areunder main controller 110 control.

Initially, the tumor containing volume of the patient 2130 is positionedand immobilized 3810 in a controlled and reproducible position. Theprocess of positioning and immobilizing 3810 the patient 2310 ispreferably iterated 4312 until the position is accepted. The position ispreferably digitally recorded 4315 and is later used in a step ofcomputer controlled repositioning of the patient 4317 in the minutes orseconds prior to implementation of the irradiation element 3840 of thetumor treatment plan. The process of positioning the patient in areproducible fashion and reproducibly aligning the patient 2310 to thecontrolled position is further described, infra.

Subsequent to patient positioning 3810, the steps of monitoring 4010 andpreferably controlling 4020 the respiration cycle of the patient 2130are preferably performed to yield more precise positioning of the tumor2120 relative to other body constituents, as described supra.Multi-field images of the tumor are then collected 4340 in thecontrolled, immobilized, and reproducible position. For example,multi-field X-ray images of the tumor 2120 are collected using the X-raysource proximate the proton beam path, as described supra. Themulti-field images are optionally from three or more positions and/orare collected while the patient is rotated, as described supra.

At this point the patient 2130 is either maintained in the treatmentposition or is allowed to move from the controlled treatment positionwhile an oncologist processes the multi-field images 4345 and generatesa tumor treatment plan 4350 using the multi-field images. Optionally,the tumor irradiation plan is implemented 3840 at this point in time.

Typically, in a subsequent treatment center visit, the patient 2130 isrepositioned 4317. Preferably, the patient's respiration cycle is againmonitored 4012 and/or controlled 4022, such as via use of the thermalmonitoring respiration sensors, force monitoring respiration sensor,and/or via commands sent to the display monitor 3390, described supra.Once repositioned, verification images are collected 4360, such as X-raylocation verification images from 1, 2, or 3 directions. For example,verification images are collected with the patient facing the protonbeam and at rotation angles of 90, 180, and 270 degrees from thisposition. At this point, comparing the verification images to theoriginal multi-field images used in generating the treatment plan, thealgorithm or preferably the oncologist determines if the tumor 2120 issufficiently repositioned 4365 relative to other body parts to allow forinitiation of tumor irradiation using the charged particle beam.Essentially, the step of accepting the final position of the patient4365 is a safety feature used to verify that that the tumor 2120 in thepatient 2130 has not shifted or grown beyond set specifications. At thispoint the charged particle beam therapy commences 3840. Preferably thepatient's respiration is monitored 4014 and/or controlled 4024, asdescribed supra, prior to commencement of the charged particle beamtreatment 3840.

Optionally, simultaneous X-ray imaging 4390 of the tumor 2120 isperformed during the multi-field proton beam irradiation procedure andthe main controller 110 uses the X-ray images to adapt the radiationtreatment plan in real-time to account for small variations in movementof the tumor 2120 within the patient 2130.

Herein the steps of monitoring 4010, 4012, 4014 and controlling 4020,4022, 4024 the patient's respiration are optional, but preferred. Thesteps of monitoring and controlling the patient's respiration areperformed before and/or during the multi-filed imaging 4340, positionverification 4360, and/or tumor irradiation 3840 steps. The patientpositioning 3810 and patient repositioning 4317 steps are furtherdescribed, infra.

Coordinated Charged Particle Acceleration and Respiration Rate

In yet another embodiment, the charged particle accelerator issynchronized to the patient's respiration cycle. More particularly,synchrotron acceleration cycle usage efficiency is enhanced by adjustingthe synchrotron's acceleration cycle to correlate with a patient'srespiration rate. Herein, efficiency refers to the duty cycle, thepercentage of acceleration cycles used to deliver charged particles tothe tumor, and/or the fraction of time that charged particles aredelivered to the tumor from the synchrotron. The system senses patientrespiration and controls timing of negative ion beam formation,injection of charged particles into a synchrotron, acceleration of thecharged particles, and/or extraction to yield delivery of the particlesto the tumor at a predetermine period of the patient's respirationcycle. Preferably, one or more magnetic fields in the synchrotron 130are stabilized through use of a feedback loop, which allows rapidchanging of energy levels and/or timing of extraction from pulse topulse. Further, the feedback loop allows control of theacceleration/extraction to correlate with a changing patient respirationrate. Independent control of charged particle energy and intensity ismaintained during the timed irradiation therapy. Multi-field irradiationensures efficient delivery of Bragg peak energy to the tumor whilespreading ingress energy about the tumor.

In one example, a sensor, such as the first thermal sensor 3670 or thesecond thermal sensor 3660, is used to monitor a patient's respiration.A controller, such as the main controller 110, then controls chargedparticle formation and delivery to yield a charged particle beamdelivered at a determined point or duration period of the respirationcycle, which ensures precise and accurate delivery of radiation to atumor that moves during the respiration process. Optional chargedparticle therapy elements controlled by the controller include theinjector 120, accelerator 132, and/or extraction 134 system. Elementsoptionally controlled in the injector system 120 include: injection ofhydrogen gas into a negative ion source 310, generation of a high energyplasma within the negative ion source, filtering of the high energyplasma with a magnetic field, extracting a negative ion from thenegative ion source, focusing the negative ion beam 319, and/orinjecting a resulting positive ion beam 262 into the synchrotron 130.Elements optionally controlled in the accelerator 132 include:accelerator coils, applied magnetic fields in turning magnets, and/orapplied current to correction coils in the synchrotron. Elementsoptionally controlled in the extraction system 134 include:radio-frequency fields in an extraction element and/or applied fields inan extraction process. By using the respiration sensor to controldelivery of the charged particle beam to the tumor during a set periodof the respiration cycle, the period of delivery of the charged particleto the tumor is adjustable to a varying respiration rate. Thus, if thepatient breathes faster, the charged particle beam is delivered to thetumor more frequently and if the patient breathes slower, then thecharged particle beam is delivered to the tumor less frequently.Optionally, the charged particle beam is delivered to the tumor witheach breath of the patient regardless of the patient's changingrespiration rate. This lies in stark contrast with a system where thecharged particle beam delivers energy at a fixed time interval and thepatient must adjust their respiration rate to match the period of theaccelerator delivering energy and if the patient's respiration rate doesnot match the fixed period of the accelerator, then that acceleratorcycle is not delivered to the tumor and the acceleration usageefficiency is reduced.

Typically, in an accelerator the current is stabilized. A problem withcurrent stabilized accelerators is that the magnets used have memoriesin terms of both magnitude and amplitude of a sine wave. Hence, in atraditional system, in order to change the circulation frequency of thecharged particle beam in a synchrotron, slow changes in current must beused. However, in a second example, the magnetic field controlling thecirculation of the charged particles about the synchrotron isstabilized. The magnetic field is stabilized through use of: (1)magnetic field sensors 1650 sensing the magnetic field about thecirculating charged particles and (2) a feedback loop through acontroller or main controller 110 controlling the magnetic field aboutthe circulating charged particles. The feedback loop is optionally usedas a feedback control to the first winding coil 1250 and the secondwinding coil 1260. However, preferably the feedback loop is used tocontrol the correction coils 1510, 1520, described supra. With the useof the feedback loop described herein using the magnetic field sensors,the frequency and energy level of the synchrotron are rapidly adjustableand the problem is overcome. Further, the use of the smaller correctioncoils 1510, 1520 allows for rapid adjustment of the accelerator comparedto the use of the larger winding coils 1250, 1260, described supra. Moreparticularly, the feedback control allows an adjustment of theaccelerator energy from pulse to pulse in the synchrotron 130.

In this section, the first example yielded delivery of the chargedparticle beam during a particular period of the patient's respirationcycle even if the patient's respiration period is varying. In thissection, the second example used a magnetic field sensor 1650 and afeedback loop to the correction coils 1510, 1520 to rapidly adjust theenergy of the accelerator from pulse to pulse. In a third example, therespiration sensor of the first example is combined with the magneticfield sensor of the second example to control both the timing of thedelivery of the charged particle beam from the accelerator and theenergy of the charged particle beam from the accelerator. Moreparticularly, the timing of the charged particle delivery is controlledusing the respiration sensor, as described supra, and the energy of thecharged particle beam is controlled using the magnetic filed sensors andfeedback loop, as described supra. Still more particularly, a magneticfield controller, such as the main controller 110, takes the input fromthe respiration sensor and uses the input as: (1) a feedback control tothe magnetic fields controlling the circulating charged particles energyand (2) as a feedback control to time the pulse of the charged particleaccelerator to the respiration cycle of the patient. This combinationallows delivery of the charged particle beam to the tumor with eachbreath of the patient even if the breathing rate of the patient varies.In this manner, the accelerator efficiency is increased as the cancertherapy system does not need to lose cycles when the patient's breathingis not in phase with the synchrotron charged particle generation rate.

Referring now to FIG. 44, the combined use of the respiration sensor andmagnetic field sensor 4400 to deliver charged particles at varyingenergy and at varying time intervals is further described. The maincontroller 110 controls the injection system 120, charged particleacceleration system 132, extraction system 134, and targeting/deliverysystem 140. In this embodiment, the previously described respirationmonitoring system 4410 of the patient interface module 150 is used as aninput to a magnetic field controller 4420. A second input to themagnetic field controller 4420 is a magnetic field sensor 1650. In onecase, the respiration rates from the respiration monitoring system 4410are fed to the main controller 130, which controls the injection system120 and/or components of the acceleration system 132 to yield a chargedparticle beam at a chosen period of the respiration cycle, as describedsupra. In a second case, the respiration data from the respirationmonitoring system is used as an input to the magnetic field controller4420. The magnetic field controller also receives feedback input fromthe magnetic field sensor 1650. The magnetic field controller thus timescharged particle energy delivery to correlate with sensed respirationrates and delivers energy levels of the charged particle beam that arerapidly adjustable with each pulse of the accelerator using the feedbackloop through the magnetic field sensor 1650.

Referring still to FIG. 44 and now additionally referring to FIG. 45, afurther example is used to clarify the magnetic field control using afeedback loop 4400 to change delivery times and/or periods of protonpulse delivery. In one case, a respiratory sensor 4410 senses therespiration cycle of the patient. The respiratory sensor sends thepatient's respiration pattern or information to an algorithm in themagnetic field controller 4420, typically via the patient interfacemodule 150 and/or via the main controller 110 or a subcomponent thereof.The algorithm predicts and/or measures when the patient is at aparticular point in the respiration cycle, such as at the top or bottomof a breath. One or more magnetic field sensors 1650 are used as inputsto the magnetic field controller 4420, which controls a magnet powersupply for a given magnetic, such as within a first turning magnet 1010of a synchrotron 130. The control feedback loop is thus used to dial thesynchrotron to a selected energy level and to deliver protons with thedesired energy at a selected point in time, such as at a particularpoint in the respiration cycle. The selected point in the respirationcycle is optionally anywhere in the respiration cycle and/or for anyduration during the respiration cycle. As illustrated in FIG. 45, theselected time period is at the top of a breath for a period of about0.1, 0.5, 1 seconds. More particularly, the main controller 110 controlsinjection of hydrogen into the injection system, formation of thenegative ion 310, controls extraction of negative ions from negative ionsource 310, controls injection 120 of protons into the synchrotron 130,and/or controls acceleration of the protons in a manner that combinedwith extraction 134 delivers the protons 140 to the tumor at a selectedpoint in the respiration cycle. Intensity of the proton beam is alsoselectable and controllable by the main controller 130 at this stage, asdescribed supra. The feedback control from the magnetic field controller4420 is optionally to a power or power supplies for one or both of themain bending magnet 250, described supra, or to the correction coils1520 within the main bending magnet 250. Having smaller appliedcurrents, the correction coils 1510, 1520 are rapidly adjustable to anewly selected acceleration frequency or corresponding charged particleenergy level. Particularly, the magnetic field controller 4420 altersthe applied fields to the main bending magnets or correction coils thatare tied to the patient's respiration cycle. This system is in starkcontrast to a system where the current is stabilized and the synchrotrondelivers pulses with a fixed period. Preferably, the feedback of themagnetic field design coupled with the correction coils allows for theextraction cycle to match the varying respiratory rate of the patient,such as where a first respiration period 4510, P₁, does not equal asecond respiration period 4520, P₂.

Referring now to FIG. 46, an example of a charged particle cancertherapy system 100 is provided. A main controller receives input fromone, two, three, or four of a respiration monitoring and/or controllingcontroller 4610, a beam controller 4615, a rotation controller 4650,and/or a timing to a time period in a respiration cycle controller 4660.The beam controller 4615 preferably includes one or more or a beamenergy controller 4620, the beam intensity controller 1940, a beamvelocity controller 4630, and/or a horizontal/vertical beam positioningcontroller 4640. The main controller 110 controls any element of theinjection system 120; the synchrotron 130; thescanning/targeting/delivery system 140; the patient interface module150; the display system 160; and/or the imaging system 170. For example,the respiration monitoring/controlling controller 4610 controls anyelement or method associated with the respiration of the patient; thebeam controller 4615 controls any of the elements controllingacceleration and/or extraction of the charged particle beam; therotation controller 4650 controls any element associated with rotationof the patient 2130 or gantry; and the timing to a period in respirationcycle controller 4660 controls any aspects affecting delivery time ofthe charged particle beam to the patient. As a further example, the beamcontroller 4615 optionally controls any magnetic and/or electric fieldabout any magnet in the charged particle cancer therapy system 100.

Computer Controlled Patient Repositioning

One or more of the patient positioning unit components and/or one ofmore of the patient positioning constraints are preferably undercomputer control. For example, the computer records or controls theposition of the patient positioning elements 3315, such as via recordinga series of motor positions connected to drives that move the patientpositioning elements 3315. For example, the patient is initiallypositioned 3810 and constrained by the patient positioning constraints3315. The position of each of the patient positioning constraints isrecorded and saved by the main controller 110, by a sub-controller ofthe main controller 110, or by a separate computer controller. Then,imaging systems are used to locate the tumor 2120 in the patient 2130while the patient is in the controlled position of final treatment.Preferably, when the patient is in the controlled position, multi-fieldimaging is performed, as described herein. The imaging system 170includes one or more of: MRI's, X-rays, CT's, proton beam tomography,and the like. Time optionally passes at this point while images from theimaging system 170 are analyzed and a proton therapy treatment plan isdevised. The patient optionally exits the constraint system during thistime period, which may be minutes, hours, or days. Upon, and preferablyafter, return of the patient and initial patient placement into thepatient positioning unit, the computer returns the patient positioningconstraints to the recorded positions. This system allows for rapidrepositioning of the patient to the position used during imaging anddevelopment of the multi-field charged particle irradiation treatmentplan, which minimizes setup time of patient positioning and maximizestime that the charged particle beam system 100 is used for cancertreatment.

Reproducing Patient Positioning and Immobilization

In one embodiment, using a patient positioning and immobilization system4000, a region of the patient 2130 about the tumor 2120 is reproduciblypositioned and immobilized, such as with the motorized patienttranslation and rotation positioning system 2110 and/or with the patientpositioning constraints 3315. For example, one of the above describedpositioning systems, such as (1) the semi-vertical partialimmobilization system 3300; (2) the sitting partial immobilizationsystem 3400; or (3) the laying position system 3500 is used incombination with the patient translation and rotation system 2110 toposition the tumor 2120 of the patient 2130 relative to the proton beampath 268. Preferably, the position and immobilization system controlsposition of the tumor 2120 relative to the proton beam path 268,immobilizes position of the tumor 2120, and facilitates repositioningthe tumor 2120 relative to the proton beam path 268 after the patient2130 has moved away from the proton beam path 268, such as duringdevelopment of the irradiation treatment plan 4345.

Preferably, the tumor 2120 of the patient 2130 is positioned in terms of3-D location and in terms of orientation attitude. Herein, 3-D locationis defined in terms of the x-, y-, and z-axes and orientation attitudeis the state of pitch, yaw, and roll. Roll is rotation of a plane aboutthe z-axis, pitch is rotation of a plane about the x-axis, and yaw isthe rotation of a plane about the y-axis. Tilt is used to describe bothroll and pitch. Preferably, the positioning and immobilization systemcontrols the tumor 2120 location relative to the proton beam path 268 interms of at least three of and preferably in terms of four, five, or sixof: pitch, yaw, roll, x-axis location, y-axis location, and z-axislocation.

Chair

The patient positioning and immobilization system 4000 is furtherdescribed using a chair positioning example. For clarity, a case ofpositioning and immobilizing a tumor in a shoulder is described usingchair positioning. Using the semi-vertical immobilization system 3300,the patient is generally positioned using the seat support 3320, kneesupport 3360, and/or foot support 3370. To further position theshoulder, a motor in the back support 3330 pushes against the torso ofthe patient. Additional arm support 3350 motors align the arm, such asby pushing with a first force in one direction against the elbow of thepatient and the wrist of the patient is positioned using a second forcein a counter direction. This restricts movement of the arm, which helpsto position the shoulder. Optionally, the head support is positioned tofurther restrict movement of the shoulder by applying tension to theneck. Combined, the patient positioning constraints 3315 controlposition of the tumor 2120 of the patient 2130 in at least threedimensions and preferably control position of the tumor 2120 in terms ofall of yaw, roll, and pitch movement as well as in terms of x-, y-, andz-axis position. For instance, the patient positioning constraintsposition the tumor 2120 and restricts movement of the tumor, such as bypreventing patient slumping. Optionally, sensors in one or more of thepatient positioning constraints 3315 record an applied force. In onecase, the seat support senses weight and applies a force to support afraction of the patient's weight, such as about 50, 60, 70, or 80percent of the patient's weight. In a second case, a force applied tothe neck, arm, and/or leg is recorded.

Generally, the patient positioning and immobilization system 4000removes movement degrees of freedom from the patient 2130 to accuratelyand precisely position and control the position of the tumor 2120relative to the X-ray beam path 3070, proton beam path 268, and/or animaging beam path. Further, once the degrees of freedom are removed, themotor positions for each of the patient positioning constraints arerecorded and communicated digitally to the main controller 110. Once thepatient moves from the immobilization system 4000, such as when theirradiation treatment plan is generated 4350, the patient 2130 must beaccurately repositioned in a patient repositioning system 4300 beforethe irradiation plan is implemented. To accomplish this, the patient2130 sits generally in the positioning device, such as the chair, andthe main controller sends the motor position signals and optionally theapplied forces back to motors controlling each of the patientpositioning constraints 3315 and each of the patient positioningconstraints 3315 are automatically moved back to their respectiverecorded positions. Hence, re-positioning and re-immobilizing thepatient 2130 is accomplished from a time of sitting to fully controlledposition in less than about 10, 30, 60, 120, or 600 seconds.

Using the computer controlled and automated patient positioning system,the patient is re-positioned in the positioning and immobilizationsystem 4300 using the recalled patient positioning constraint 3315 motorpositions; the patient 2130 is translated and rotated using the patienttranslation and rotation system 2120 relative to the proton beam 268;and the proton beam 268 is scanned to its momentary beam position 269 bythe main controller 110, which follows the generated irradiationtreatment plan 4350.

Tomography

In one embodiment, the charged particle tomography apparatus is used toimage a tumor in a patient.

In another embodiment, the charged particle tomography apparatus is usedin combination with a charged particle cancer therapy system usingcommon elements. For example, tomographic imaging of a cancerous tumoris performed using charged particles generated with an injector,accelerator, and guided with a delivery system that are part of thecancer therapy system, described supra.

In various embodiments, the tomography imaging system is optionallysimultaneously operational with a charged particle cancer therapy systemusing common elements, allows tomographic imaging with rotation of thepatient, is operational on a patient in an upright, semi-upright, and/orhorizontal position, is simultaneously operational with X-ray imaging,and/or allows use of adaptive charged particle cancer therapy. Further,the common tomography and cancer therapy apparatus elements areoptionally operational in a multi-axis and/or multi-field raster beammode.

In conventional medical X-ray tomography, a sectional image through abody is made by moving one or both of an X-ray source and the X-ray filmin opposite directions during the exposure. By modifying the directionand extent of the movement, operators can select different focal planes,which contain the structures of interest. More modern variations oftomography involve gathering projection data from multiple directions bymoving the X-ray source and feeding the data into a tomographicreconstruction software algorithm processed by a computer. Herein, instark contrast to known methods, the radiation source is a chargedparticle, such as a proton ion beam or a carbon ion beam. A proton beamis used herein to describe the tomography system, but the descriptionapplies to a heavier ion beam, such as a carbon ion beam. Further, instark contrast to known techniques, herein the radiation source ispreferably stationary while the patient is rotated.

Referring now to FIG. 47, an example of a tomography apparatus isdescribed. In one example, the tomography system 4700 uses elements incommon with the charged particle beam system 100, including elements ofone or more of the injection system 120, accelerator 130,targeting/delivery system 140, patient interface module 150, displaysystem 160, and/or imaging system 170, such as the X-ray imaging system.Preferably, a scintillation plate 4710, such as a scintillating plasticis positioned behind the patient 2130 relative to the targeting/deliverysystem 140 elements. The charged particle beam system 100 as describedhas proven operation at up to and including 330 MeV, which is sufficientto send protons through the body and into contact with the scintillationmaterial. The intensity or count of protons hitting the plate as afunction of position is used to create an image. The patient 2130 isrotated 2117 about the y-axis and a new image is collected. Preferably,a new image is collected with about every one degree of rotation of thepatient resulting in about 360 images that are combined into a tomogramusing tomographic reconstruction software. The tomographicreconstruction software uses overlapping rotationally varied images inthe reconstruction. Optionally, a new image is collected at about every2, 3, 4, 5, 10, 15, 30, or 45 degrees of rotation of the patient.

In one embodiment, a tomogram or an individual tomogram section image iscollected at about the same time as cancer therapy occurs using thecharged particle beam system. For example, an tomogram is collected andcancer therapy is subsequently performed: without the patient movingfrom the positioning systems, such as the above described semi-verticalpartial immobilization system 3300, the sitting partial immobilizationsystem 3400, or the a laying position 3500. In a second example, anindividual tomogram slice is collected using a first cycle of theaccelerator 130 and using a following cycle of the accelerator 130, thetumor 2120 is irradiated, such as within about 1, 2, 5, 10, or 30seconds. In a third case, about 2, 3, 4, or 5 tomogram slices arecollected using 1, 2, 3, 4, or more rotation positions of the patient2130 within about 5, 10, 15, 30, or 60 seconds of subsequent tumorirradiation therapy.

In another embodiment, the independent control of the tomographicimaging process and X-ray collection process allows simultaneous singleand/or multi-field collection of X-ray images and tomographic imageseasing interpretation of multiple images. Indeed, the X-ray andtomographic images are optionally overlaid to from a hybrid X-ray/protonbeam tomographic image as the patient is optionally in the same positionfor each image.

In still another embodiment, the tomogram is collected with the patient2130 in the about the same position as when the patient's tumor istreated using subsequent irradiation therapy. For some tumors, thepatient being positioned in the same upright or semi-upright positionallows the tumor 2120 to be separated from surrounding organs or tissueof the patient 2130 better than in a laying position. Positioning of thescintillation plate 4710 behind the patient 2130 allows the tomographicimaging to occur while the patient is in the same upright orsemi-upright position.

The use of common elements in the tomographic imaging and in the chargedparticle cancer therapy allows benefits of the cancer therapy, describedsupra, to optionally be used with the tomographic imaging, such asproton beam x-axis control, proton beam y-axis control, control ofproton beam energy, control of proton beam intensity, timing control ofbeam delivery to the patient, rotation control of the patient, andcontrol of patient translation all in a raster beam mode of protonenergy delivery.

In yet still another embodiment, initially a three-dimensionaltomographic proton based reference image is collected, such as withhundreds of individual rotation images of the tumor 2120 and patient2130. Subsequently, just prior to proton treatment of the cancer, just afew 2-dimensional control tomographic images of the patient arecollected, such as with a stationary patient or at just a few rotationpositions, such as an image straight on to the patient, with the patientrotated about 45 degrees each way, and/or the patient rotated about 90degrees each way about the y-axis. The individual control images arecompared with the 3-dimensional reference image. An adaptive protontherapy is subsequently performed where: (1) the proton cancer therapyis not used for a given position based on the differences between the3-dimensional reference image and one or more of the 2-dimensionalcontrol images and/or (2) the proton cancer therapy is modified in realtime based on the differences between the 3-dimensional reference imageand one or more of the 2-dimensional control images

Still yet another embodiment includes any combination and/or permutationof any of the elements described herein.

The particular implementations shown and described are illustrative ofthe invention and its best mode and are not intended to otherwise limitthe scope of the present invention in any way. Indeed, for the sake ofbrevity, conventional manufacturing, connection, preparation, and otherfunctional aspects of the system may not be described in detail.Furthermore, the connecting lines shown in the various figures areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. Many alternative or additionalfunctional relationships or physical connections may be present in apractical system.

In the foregoing description, the invention has been described withreference to specific exemplary embodiments; however, it will beappreciated that various modifications and changes may be made withoutdeparting from the scope of the present invention as set forth herein.The description and figures are to be regarded in an illustrativemanner, rather than a restrictive one and all such modifications areintended to be included within the scope of the present invention.Accordingly, the scope of the invention should be determined by thegeneric embodiments described herein and their legal equivalents ratherthan by merely the specific examples described above. For example, thesteps recited in any method or process embodiment may be executed in anyorder and are not limited to the explicit order presented in thespecific examples. Additionally, the components and/or elements recitedin any apparatus embodiment may be assembled or otherwise operationallyconfigured in a variety of permutations to produce substantially thesame result as the present invention and are accordingly not limited tothe specific configuration recited in the specific examples.

Benefits, other advantages and solutions to problems have been describedabove with regard to particular embodiments; however, any benefit,advantage, solution to problems or any element that may cause anyparticular benefit, advantage or solution to occur or to become morepronounced are not to be construed as critical, required or essentialfeatures or components.

As used herein, the terms “comprises”, “comprising”, or any variationthereof, are intended to reference a non-exclusive inclusion, such thata process, method, article, composition or apparatus that comprises alist of elements does not include only those elements recited, but mayalso include other elements not expressly listed or inherent to suchprocess, method, article, composition or apparatus. Other combinationsand/or modifications of the above-described structures, arrangements,applications, proportions, elements, materials or components used in thepractice of the present invention, in addition to those not specificallyrecited, may be varied or otherwise particularly adapted to specificenvironments, manufacturing specifications, design parameters or otheroperating requirements without departing from the general principles ofthe same.

Although the invention has been described herein with reference tocertain preferred embodiments, one skilled in the art will readilyappreciate that other applications may be substituted for those setforth herein without departing from the spirit and scope of the presentinvention.

1. An apparatus for extracting a circulating charged particle beam froma synchrotron, said synchrotron having a center, said apparatuscomprising: a set of n extraction foils, wherein n is a positive integerof at least two; at least a one kilovolt direct current field appliedacross a pair of extraction blades; and a deflector, wherein thecirculating charged particle beam passes through at least one of said nextraction foils resulting in a reduced energy charged particle beam,wherein the reduced energy charged particle beam passes between saidpair of extraction blades, and wherein the direct current fieldredirects the reduced energy charged particle beam through saiddeflector, wherein said deflector yields an extracted charged particlebeam.
 2. The apparatus of claim 1, wherein said set of n extractionfoils comprises: a first extraction foil; a second extraction foil; anda third extraction foil.
 3. The apparatus of claim 2, wherein said firstextraction foil comprises a first thickness, wherein said secondextraction foil comprises a second thickness, wherein said thirdextraction foil comprises a third thickness, wherein said firstthickness is less than said second thickness, wherein said secondthickness is less than said third thickness.
 4. The apparatus of claim2, wherein said first foil comprises a thickness in the range of 30 to70 micrometers, wherein said second foil comprises a thickness in therange of 60 to 140 micrometers, wherein said third foil comprises athickness in the range of 150 to 250 micrometers.
 5. The apparatus ofclaim 1, further comprising: an actuator configured to alternately movea foil of said set of n extraction foils toward said center of saidsynchrotron and away from said center of said synchrotron.
 6. Theapparatus of claim 1, wherein a first extraction foil of said set of nextraction foils comprises a first density at least ten percent lessthan a second density of a second extraction foil of said set of nextraction foils.
 7. The apparatus of claim 1, wherein at least one foilof said set of said set of n extraction foils comprises a chemical formof any of: beryllium; lithium hydride; and carbon.
 8. The apparatus ofclaim 1, wherein the circulating charged particle beam comprises a firstradius of curvature greater than a second radius of curvature of thereduced energy charged particle beam passing through said extractionblades.
 9. The apparatus of claim 1, further comprising: an intensitycontroller controlling intensity of the extracted charged particle beamvia a feedback control, wherein an induced current results from thecirculating charged particle beam passing through at least one of said nextraction foils, wherein the induced current comprises a feedback inputto said intensity controller.
 10. A method for extracting a circulatingcharged particles from a synchrotron, comprising the steps of: providinga set of n extraction foils, wherein n is a positive integer of at leasttwo; transmitting the circulating charged particles through at least onefoil of said set of n extraction foils, said foil yielding reducedenergy charged particles; applying at least five hundred volts across afirst pair of blades; and passing the reduced energy charged particlesbetween said first pair of blades, wherein said first pair of bladesredirect the reduced energy charged particles to a deflector, andwherein said deflector yields extracted charged particles.
 11. Themethod of claim 10, further comprising the step of: using a first foil,of said set of n foils, in the extraction of charged particlescomprising an energy less than 150 MeV; and using a second foil, of saidset of n foils, in the extraction of charged particles comprising anenergy in excess of 150 MeV.
 12. The method of claim 10, furthercomprising the steps of: moving at least one foil of said set of nextraction foils toward said center of said synchrotron prior to saidstep of passing; and moving said at least one foil away from said centerof said synchrotron after said step of passing.
 13. The method of claim10, further comprising the step of: selecting a member of said set of nextraction foils using knowledge of energy of said circulating chargedparticles.
 14. The method of claim 10, further comprising the step of:selecting a first foil of said set of n extraction foils for extractionof said circulating charged particles comprising a first energy; andselecting a second foil of said set of n extraction foils for extractionof said circulating charged particles comprising a second energy, saidsecond energy at least one hundred twenty percent of said first energy.15. The method of claim 10, further comprising the step of: controllingintensity of the extracted charged particles beam with an intensitycontroller using a feedback control, wherein an induced current resultsfrom the circulating charged particles passing through at least one ofsaid set of n extraction foils, wherein the induced current comprises afeedback input to said step of controlling intensity.
 16. A method forrepetitively extracting circulating charged particles from asynchrotron, comprising the steps of: providing said synchrotron;providing a set of at least two extraction foils; selecting a member ofsaid set based on energy of the circulating charged particles; using anactuator to move said selected member of said set of extraction foilstoward a center of said synchrotron; transmitting the circulatingcharged particles through said selected member to yield a reduced energycharged particle beam; moving, with said actuator, said selected memberof said set of extraction foils away from the center of saidsynchrotron; and repeating said steps of: selecting, using,transmitting, and moving.
 17. The method of claim 16, wherein at leastone of said extraction foils consists essentially of atoms comprisingsix or fewer protons.
 18. A method for extracting circulating chargedparticles from a synchrotron, comprising the steps of: providing saidsynchrotron; providing a set of at least two extraction foils; selectinga member of said set of extraction foils based on energy of thecirculating charged particles; transmitting the circulating chargedparticles through said selected member to yield a reduced energy chargedparticle beam; and redirecting said reduced energy charged particle beamout of said synchrotron using a Lamberson magnet.
 19. The method ofclaim 18, wherein a second extraction foil of said at least twoextraction foils comprises a second thickness at least double a firstthickness of a first extraction foil of said at least two extractionfoils.
 20. The method of claim 18, further comprising the steps of:inducing a change in a radius of curvature movement of the circulatingcharged particles: (1) after acceleration of the charged particle beamto a selected energy and (2) prior to said step of transmitting thecirculating charged particle beam through said selected member; andcontrolling intensity of said extracted charged particles using anelectron flow resultant from the circulating charged particlestransmitting through said selected member.